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* [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
@ 2021-08-19  8:10 syzbot
  2021-08-19 10:03 ` Pavel Begunkov
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2021-08-19  8:10 UTC (permalink / raw)
  To: asml.silence, axboe, io-uring, linux-kernel, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    f26c3abc432a Add linux-next specific files for 20210818
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=169f1731300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d472f8be79a62b44
dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15f35e16300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161c1765300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9c3492b27d10dc49ffa6@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2031 [inline]
BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2078
Read of size 4 at addr ffff88801da62358 by task syz-executor959/7251

CPU: 0 PID: 7251 Comm: syz-executor959 Not tainted 5.14.0-rc6-next-20210818-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:442 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
 ctx_flush_and_put fs/io_uring.c:2031 [inline]
 tctx_task_work+0x307/0x310 fs/io_uring.c:2078
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x129/0x310 kernel/exit.c:922
 get_signal+0x482/0x2170 kernel/signal.c:2846
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x446749
Code: Unable to access opcode bytes at RIP 0x44671f.
RSP: 002b:00007f2e177871e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 000000000000039b RBX: 00000000004cb468 RCX: 0000000000446749
RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
RBP: 00000000004cb460 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb46c
R13: 00007ffe292df50f R14: 00007f2e17787300 R15: 0000000000022000

Allocated by task 7251:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9f/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 io_ring_ctx_alloc fs/io_uring.c:1235 [inline]
 io_uring_create fs/io_uring.c:9876 [inline]
 io_uring_setup+0x27d/0x2d00 fs/io_uring.c:9982
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 6731:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xff/0x140 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1681 [inline]
 slab_free_freelist_hook+0x82/0x190 mm/slub.c:1706
 slab_free mm/slub.c:3463 [inline]
 kfree+0xea/0x540 mm/slub.c:4523
 io_ring_ctx_free fs/io_uring.c:8902 [inline]
 io_ring_exit_work+0x13c7/0x1940 fs/io_uring.c:9051
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe9/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1353
 __queue_work+0x5d1/0xf30 kernel/workqueue.c:1519
 queue_work_on+0xf6/0x110 kernel/workqueue.c:1546
 queue_work include/linux/workqueue.h:502 [inline]
 io_ring_ctx_wait_and_kill+0x314/0x3d0 fs/io_uring.c:9104
 io_uring_release+0x3e/0x50 fs/io_uring.c:9112
 __fput+0x288/0x9f0 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x129/0x310 kernel/exit.c:922
 get_signal+0x482/0x2170 kernel/signal.c:2846
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801da62000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 856 bytes inside of
 4096-byte region [ffff88801da62000, ffff88801da63000)
The buggy address belongs to the page:
page:ffffea0000769800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1da60
head:ffffea0000769800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c42140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 254, ts 8722226076, free_ts 8721850730
 prep_new_page mm/page_alloc.c:2424 [inline]
 get_page_from_freelist+0xa76/0x2f90 mm/page_alloc.c:4151
 __alloc_pages+0x1ba/0x510 mm/page_alloc.c:5373
 alloc_pages+0x1a7/0x300 mm/mempolicy.c:2188
 alloc_slab_page mm/slub.c:1744 [inline]
 allocate_slab mm/slub.c:1881 [inline]
 new_slab+0x321/0x490 mm/slub.c:1944
 ___slab_alloc+0x90b/0xfb0 mm/slub.c:2974
 __slab_alloc.constprop.0+0x51/0xa0 mm/slub.c:3061
 slab_alloc_node mm/slub.c:3152 [inline]
 slab_alloc mm/slub.c:3194 [inline]
 kmem_cache_alloc_trace+0x30a/0x3c0 mm/slub.c:3211
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 kobject_uevent_env+0x240/0x1650 lib/kobject_uevent.c:524
 device_add+0xbc6/0x21b0 drivers/base/core.c:3340
 scsi_target_add drivers/scsi/scsi_sysfs.c:1309 [inline]
 scsi_sysfs_add_sdev+0x464/0x750 drivers/scsi/scsi_sysfs.c:1336
 scsi_sysfs_add_devices drivers/scsi/scsi_scan.c:1727 [inline]
 scsi_finish_async_scan drivers/scsi/scsi_scan.c:1812 [inline]
 do_scan_async+0x211/0x500 drivers/scsi/scsi_scan.c:1855
 async_run_entry_fn+0x9d/0x550 kernel/async.c:127
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
 worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1338 [inline]
 free_pcp_prepare+0x377/0x860 mm/page_alloc.c:1389
 free_unref_page_prepare mm/page_alloc.c:3315 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3394
 sbitmap_free include/linux/sbitmap.h:165 [inline]
 scsi_device_dev_release_usercontext+0x65a/0xd60 drivers/scsi/scsi_sysfs.c:479
 execute_in_process_context+0x37/0x160 kernel/workqueue.c:3358
 device_release+0xa3/0x240 drivers/base/core.c:2195
 kobject_cleanup lib/kobject.c:705 [inline]
 kobject_release lib/kobject.c:736 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1d0/0x540 lib/kobject.c:753
 put_device+0x1b/0x30 drivers/base/core.c:3466
 __scsi_remove_device+0x1e1/0x3e0 drivers/scsi/scsi_sysfs.c:1477
 scsi_probe_and_add_lun+0x266d/0x35a0 drivers/scsi/scsi_scan.c:1205
 __scsi_scan_target+0x229/0xdc0 drivers/scsi/scsi_scan.c:1588
 scsi_scan_channel drivers/scsi/scsi_scan.c:1676 [inline]
 scsi_scan_channel+0x148/0x1e0 drivers/scsi/scsi_scan.c:1652
 scsi_scan_host_selected+0x2df/0x3b0 drivers/scsi/scsi_scan.c:1705
 do_scsi_scan_host+0x1eb/0x260 drivers/scsi/scsi_scan.c:1844
 do_scan_async+0x3e/0x500 drivers/scsi/scsi_scan.c:1854
 async_run_entry_fn+0x9d/0x550 kernel/async.c:127
 process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297

Memory state around the buggy address:
 ffff88801da62200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801da62280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88801da62300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff88801da62380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801da62400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
  2021-08-19  8:10 [syzbot] KASAN: use-after-free Read in tctx_task_work (2) syzbot
@ 2021-08-19 10:03 ` Pavel Begunkov
  2021-08-19 10:44   ` syzbot
  0 siblings, 1 reply; 6+ messages in thread
From: Pavel Begunkov @ 2021-08-19 10:03 UTC (permalink / raw)
  To: syzbot, axboe, io-uring, linux-kernel, syzkaller-bugs

On 8/19/21 9:10 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    f26c3abc432a Add linux-next specific files for 20210818
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=169f1731300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=d472f8be79a62b44
> dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15f35e16300000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=161c1765300000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9c3492b27d10dc49ffa6@syzkaller.appspotmail.com

Can't find f26c3abc432a nor reproduce it. Let's try the latest branch.

#syz test: git://git.kernel.dk/linux-block for-5.15/io_uring


> ==================================================================
> BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2031 [inline]
> BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2078
> Read of size 4 at addr ffff88801da62358 by task syz-executor959/7251
> 
> CPU: 0 PID: 7251 Comm: syz-executor959 Not tainted 5.14.0-rc6-next-20210818-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
>  print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:256
>  __kasan_report mm/kasan/report.c:442 [inline]
>  kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
>  ctx_flush_and_put fs/io_uring.c:2031 [inline]
>  tctx_task_work+0x307/0x310 fs/io_uring.c:2078
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>  exit_task_work include/linux/task_work.h:32 [inline]
>  do_exit+0xbae/0x2a30 kernel/exit.c:825
>  do_group_exit+0x129/0x310 kernel/exit.c:922
>  get_signal+0x482/0x2170 kernel/signal.c:2846
>  arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
>  handle_signal_work kernel/entry/common.c:148 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>  exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
>  do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x446749
> Code: Unable to access opcode bytes at RIP 0x44671f.
> RSP: 002b:00007f2e177871e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
> RAX: 000000000000039b RBX: 00000000004cb468 RCX: 0000000000446749
> RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
> RBP: 00000000004cb460 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb46c
> R13: 00007ffe292df50f R14: 00007f2e17787300 R15: 0000000000022000
> 
> Allocated by task 7251:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_set_track mm/kasan/common.c:46 [inline]
>  set_alloc_info mm/kasan/common.c:434 [inline]
>  ____kasan_kmalloc mm/kasan/common.c:513 [inline]
>  ____kasan_kmalloc mm/kasan/common.c:472 [inline]
>  __kasan_kmalloc+0x9f/0xd0 mm/kasan/common.c:522
>  kmalloc include/linux/slab.h:591 [inline]
>  kzalloc include/linux/slab.h:721 [inline]
>  io_ring_ctx_alloc fs/io_uring.c:1235 [inline]
>  io_uring_create fs/io_uring.c:9876 [inline]
>  io_uring_setup+0x27d/0x2d00 fs/io_uring.c:9982
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Freed by task 6731:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
>  kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
>  ____kasan_slab_free mm/kasan/common.c:366 [inline]
>  ____kasan_slab_free mm/kasan/common.c:328 [inline]
>  __kasan_slab_free+0xff/0x140 mm/kasan/common.c:374
>  kasan_slab_free include/linux/kasan.h:230 [inline]
>  slab_free_hook mm/slub.c:1681 [inline]
>  slab_free_freelist_hook+0x82/0x190 mm/slub.c:1706
>  slab_free mm/slub.c:3463 [inline]
>  kfree+0xea/0x540 mm/slub.c:4523
>  io_ring_ctx_free fs/io_uring.c:8902 [inline]
>  io_ring_exit_work+0x13c7/0x1940 fs/io_uring.c:9051
>  process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
>  worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
>  kthread+0x3e5/0x4d0 kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> 
> Last potentially related work creation:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_record_aux_stack+0xe9/0x110 mm/kasan/generic.c:348
>  insert_work+0x48/0x370 kernel/workqueue.c:1353
>  __queue_work+0x5d1/0xf30 kernel/workqueue.c:1519
>  queue_work_on+0xf6/0x110 kernel/workqueue.c:1546
>  queue_work include/linux/workqueue.h:502 [inline]
>  io_ring_ctx_wait_and_kill+0x314/0x3d0 fs/io_uring.c:9104
>  io_uring_release+0x3e/0x50 fs/io_uring.c:9112
>  __fput+0x288/0x9f0 fs/file_table.c:280
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>  exit_task_work include/linux/task_work.h:32 [inline]
>  do_exit+0xbae/0x2a30 kernel/exit.c:825
>  do_group_exit+0x129/0x310 kernel/exit.c:922
>  get_signal+0x482/0x2170 kernel/signal.c:2846
>  arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
>  handle_signal_work kernel/entry/common.c:148 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>  exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
>  do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> The buggy address belongs to the object at ffff88801da62000
>  which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 856 bytes inside of
>  4096-byte region [ffff88801da62000, ffff88801da63000)
> The buggy address belongs to the page:
> page:ffffea0000769800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1da60
> head:ffffea0000769800 order:3 compound_mapcount:0 compound_pincount:0
> flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010c42140
> raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 254, ts 8722226076, free_ts 8721850730
>  prep_new_page mm/page_alloc.c:2424 [inline]
>  get_page_from_freelist+0xa76/0x2f90 mm/page_alloc.c:4151
>  __alloc_pages+0x1ba/0x510 mm/page_alloc.c:5373
>  alloc_pages+0x1a7/0x300 mm/mempolicy.c:2188
>  alloc_slab_page mm/slub.c:1744 [inline]
>  allocate_slab mm/slub.c:1881 [inline]
>  new_slab+0x321/0x490 mm/slub.c:1944
>  ___slab_alloc+0x90b/0xfb0 mm/slub.c:2974
>  __slab_alloc.constprop.0+0x51/0xa0 mm/slub.c:3061
>  slab_alloc_node mm/slub.c:3152 [inline]
>  slab_alloc mm/slub.c:3194 [inline]
>  kmem_cache_alloc_trace+0x30a/0x3c0 mm/slub.c:3211
>  kmalloc include/linux/slab.h:591 [inline]
>  kzalloc include/linux/slab.h:721 [inline]
>  kobject_uevent_env+0x240/0x1650 lib/kobject_uevent.c:524
>  device_add+0xbc6/0x21b0 drivers/base/core.c:3340
>  scsi_target_add drivers/scsi/scsi_sysfs.c:1309 [inline]
>  scsi_sysfs_add_sdev+0x464/0x750 drivers/scsi/scsi_sysfs.c:1336
>  scsi_sysfs_add_devices drivers/scsi/scsi_scan.c:1727 [inline]
>  scsi_finish_async_scan drivers/scsi/scsi_scan.c:1812 [inline]
>  do_scan_async+0x211/0x500 drivers/scsi/scsi_scan.c:1855
>  async_run_entry_fn+0x9d/0x550 kernel/async.c:127
>  process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
>  worker_thread+0x65b/0x1200 kernel/workqueue.c:2444
>  kthread+0x3e5/0x4d0 kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> page last free stack trace:
>  reset_page_owner include/linux/page_owner.h:24 [inline]
>  free_pages_prepare mm/page_alloc.c:1338 [inline]
>  free_pcp_prepare+0x377/0x860 mm/page_alloc.c:1389
>  free_unref_page_prepare mm/page_alloc.c:3315 [inline]
>  free_unref_page+0x19/0x690 mm/page_alloc.c:3394
>  sbitmap_free include/linux/sbitmap.h:165 [inline]
>  scsi_device_dev_release_usercontext+0x65a/0xd60 drivers/scsi/scsi_sysfs.c:479
>  execute_in_process_context+0x37/0x160 kernel/workqueue.c:3358
>  device_release+0xa3/0x240 drivers/base/core.c:2195
>  kobject_cleanup lib/kobject.c:705 [inline]
>  kobject_release lib/kobject.c:736 [inline]
>  kref_put include/linux/kref.h:65 [inline]
>  kobject_put+0x1d0/0x540 lib/kobject.c:753
>  put_device+0x1b/0x30 drivers/base/core.c:3466
>  __scsi_remove_device+0x1e1/0x3e0 drivers/scsi/scsi_sysfs.c:1477
>  scsi_probe_and_add_lun+0x266d/0x35a0 drivers/scsi/scsi_scan.c:1205
>  __scsi_scan_target+0x229/0xdc0 drivers/scsi/scsi_scan.c:1588
>  scsi_scan_channel drivers/scsi/scsi_scan.c:1676 [inline]
>  scsi_scan_channel+0x148/0x1e0 drivers/scsi/scsi_scan.c:1652
>  scsi_scan_host_selected+0x2df/0x3b0 drivers/scsi/scsi_scan.c:1705
>  do_scsi_scan_host+0x1eb/0x260 drivers/scsi/scsi_scan.c:1844
>  do_scan_async+0x3e/0x500 drivers/scsi/scsi_scan.c:1854
>  async_run_entry_fn+0x9d/0x550 kernel/async.c:127
>  process_one_work+0x9c9/0x16b0 kernel/workqueue.c:2297
> 
> Memory state around the buggy address:
>  ffff88801da62200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff88801da62280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff88801da62300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                                     ^
>  ffff88801da62380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff88801da62400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
  2021-08-19 10:03 ` Pavel Begunkov
@ 2021-08-19 10:44   ` syzbot
  2021-08-19 11:13     ` Pavel Begunkov
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2021-08-19 10:44 UTC (permalink / raw)
  To: asml.silence, axboe, io-uring, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in tctx_task_work

==================================================================
BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2002 [inline]
BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2049
Read of size 4 at addr ffff888029d66358 by task syz-executor530/27775

CPU: 0 PID: 27775 Comm: syz-executor530 Not tainted 5.14.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 ctx_flush_and_put fs/io_uring.c:2002 [inline]
 tctx_task_work+0x307/0x310 fs/io_uring.c:2049
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2808
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x446729
Code: Unable to access opcode bytes at RIP 0x4466ff.
RSP: 002b:00007fada1a521e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 00000000000001d2 RBX: 00000000004cb458 RCX: 0000000000446729
RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
RBP: 00000000004cb450 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb45c
R13: 00007ffff39bb49f R14: 00007fada1a52300 R15: 0000000000022000

Allocated by task 27776:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 ____kasan_kmalloc mm/kasan/common.c:472 [inline]
 __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:591 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 io_ring_ctx_alloc fs/io_uring.c:1206 [inline]
 io_uring_create fs/io_uring.c:9685 [inline]
 io_uring_setup+0x27d/0x2cf0 fs/io_uring.c:9791
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 10491:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:230 [inline]
 slab_free_hook mm/slub.c:1625 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1650
 slab_free mm/slub.c:3210 [inline]
 kfree+0xe4/0x530 mm/slub.c:4264
 io_ring_ctx_free fs/io_uring.c:8712 [inline]
 io_ring_exit_work+0x13ba/0x1930 fs/io_uring.c:8861
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1332
 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
 queue_work_on+0xee/0x110 kernel/workqueue.c:1525
 queue_work include/linux/workqueue.h:507 [inline]
 io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
 io_uring_release+0x3e/0x50 fs/io_uring.c:8922
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2808
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 insert_work+0x48/0x370 kernel/workqueue.c:1332
 __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
 queue_work_on+0xee/0x110 kernel/workqueue.c:1525
 queue_work include/linux/workqueue.h:507 [inline]
 io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
 io_uring_release+0x3e/0x50 fs/io_uring.c:8922
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:32 [inline]
 do_exit+0xbae/0x2a30 kernel/exit.c:825
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2160 kernel/signal.c:2808
 arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888029d66000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 856 bytes inside of
 4096-byte region [ffff888029d66000, ffff888029d67000)
The buggy address belongs to the page:
page:ffffea0000a75800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29d60
head:ffffea0000a75800 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010842140
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6467, ts 58396905717, free_ts 57689976074
 prep_new_page mm/page_alloc.c:2436 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4169
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5391
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
 alloc_slab_page mm/slub.c:1688 [inline]
 allocate_slab+0x32e/0x4b0 mm/slub.c:1828
 new_slab mm/slub.c:1891 [inline]
 new_slab_objects mm/slub.c:2637 [inline]
 ___slab_alloc+0x4ba/0x820 mm/slub.c:2800
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2840
 slab_alloc_node mm/slub.c:2922 [inline]
 slab_alloc mm/slub.c:2964 [inline]
 __kmalloc+0x312/0x330 mm/slub.c:4108
 kmalloc include/linux/slab.h:596 [inline]
 tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822
 security_inode_getattr+0xcf/0x140 security/security.c:1332
 vfs_getattr fs/stat.c:139 [inline]
 vfs_statx+0x164/0x390 fs/stat.c:207
 vfs_fstatat fs/stat.c:225 [inline]
 vfs_lstat include/linux/fs.h:3386 [inline]
 __do_sys_newlstat+0x91/0x110 fs/stat.c:380
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1346 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1397
 free_unref_page_prepare mm/page_alloc.c:3332 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3411
 qlink_free mm/kasan/quarantine.c:146 [inline]
 qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
 __kasan_slab_alloc+0x8e/0xa0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook mm/slab.h:519 [inline]
 slab_alloc_node mm/slub.c:2956 [inline]
 slab_alloc mm/slub.c:2964 [inline]
 kmem_cache_alloc+0x285/0x4a0 mm/slub.c:2969
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
 getname_flags include/linux/audit.h:319 [inline]
 getname+0x8e/0xd0 fs/namei.c:209
 do_sys_openat2+0xf5/0x420 fs/open.c:1198
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_open fs/open.c:1228 [inline]
 __se_sys_open fs/open.c:1224 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1224
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888029d66200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029d66280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888029d66300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff888029d66380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029d66400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         bdd748b6 io-wq: move nr_running and worker_refs out of..
git tree:       git://git.kernel.dk/linux-block for-5.15/io_uring
console output: https://syzkaller.appspot.com/x/log.txt?x=13141b61300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb4282936412304f
dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
  2021-08-19 10:44   ` syzbot
@ 2021-08-19 11:13     ` Pavel Begunkov
  2021-08-19 17:25       ` syzbot
  0 siblings, 1 reply; 6+ messages in thread
From: Pavel Begunkov @ 2021-08-19 11:13 UTC (permalink / raw)
  To: syzbot, axboe, io-uring, linux-kernel, syzkaller-bugs

On 8/19/21 11:44 AM, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> KASAN: use-after-free Read in tctx_task_work
> 
> ==================================================================
> BUG: KASAN: use-after-free in ctx_flush_and_put fs/io_uring.c:2002 [inline]
> BUG: KASAN: use-after-free in tctx_task_work+0x307/0x310 fs/io_uring.c:2049
> Read of size 4 at addr ffff888029d66358 by task syz-executor530/27775

#syz test: https://github.com/isilence/linux.git syztest_ctx_tw

> 
> CPU: 0 PID: 27775 Comm: syz-executor530 Not tainted 5.14.0-rc5-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
>  print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
>  __kasan_report mm/kasan/report.c:419 [inline]
>  kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
>  ctx_flush_and_put fs/io_uring.c:2002 [inline]
>  tctx_task_work+0x307/0x310 fs/io_uring.c:2049
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>  exit_task_work include/linux/task_work.h:32 [inline]
>  do_exit+0xbae/0x2a30 kernel/exit.c:825
>  do_group_exit+0x125/0x310 kernel/exit.c:922
>  get_signal+0x47f/0x2160 kernel/signal.c:2808
>  arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
>  handle_signal_work kernel/entry/common.c:148 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>  exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
>  do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x446729
> Code: Unable to access opcode bytes at RIP 0x4466ff.
> RSP: 002b:00007fada1a521e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
> RAX: 00000000000001d2 RBX: 00000000004cb458 RCX: 0000000000446729
> RDX: 0000000000000000 RSI: 0000000000006b46 RDI: 0000000000000006
> RBP: 00000000004cb450 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004cb45c
> R13: 00007ffff39bb49f R14: 00007fada1a52300 R15: 0000000000022000
> 
> Allocated by task 27776:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_set_track mm/kasan/common.c:46 [inline]
>  set_alloc_info mm/kasan/common.c:434 [inline]
>  ____kasan_kmalloc mm/kasan/common.c:513 [inline]
>  ____kasan_kmalloc mm/kasan/common.c:472 [inline]
>  __kasan_kmalloc+0x9b/0xd0 mm/kasan/common.c:522
>  kmalloc include/linux/slab.h:591 [inline]
>  kzalloc include/linux/slab.h:721 [inline]
>  io_ring_ctx_alloc fs/io_uring.c:1206 [inline]
>  io_uring_create fs/io_uring.c:9685 [inline]
>  io_uring_setup+0x27d/0x2cf0 fs/io_uring.c:9791
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Freed by task 10491:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
>  kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
>  ____kasan_slab_free mm/kasan/common.c:366 [inline]
>  ____kasan_slab_free mm/kasan/common.c:328 [inline]
>  __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
>  kasan_slab_free include/linux/kasan.h:230 [inline]
>  slab_free_hook mm/slub.c:1625 [inline]
>  slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1650
>  slab_free mm/slub.c:3210 [inline]
>  kfree+0xe4/0x530 mm/slub.c:4264
>  io_ring_ctx_free fs/io_uring.c:8712 [inline]
>  io_ring_exit_work+0x13ba/0x1930 fs/io_uring.c:8861
>  process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
>  worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
>  kthread+0x3e5/0x4d0 kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> 
> Last potentially related work creation:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
>  insert_work+0x48/0x370 kernel/workqueue.c:1332
>  __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
>  queue_work_on+0xee/0x110 kernel/workqueue.c:1525
>  queue_work include/linux/workqueue.h:507 [inline]
>  io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
>  io_uring_release+0x3e/0x50 fs/io_uring.c:8922
>  __fput+0x288/0x920 fs/file_table.c:280
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>  exit_task_work include/linux/task_work.h:32 [inline]
>  do_exit+0xbae/0x2a30 kernel/exit.c:825
>  do_group_exit+0x125/0x310 kernel/exit.c:922
>  get_signal+0x47f/0x2160 kernel/signal.c:2808
>  arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
>  handle_signal_work kernel/entry/common.c:148 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>  exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
>  do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Second to last potentially related work creation:
>  kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
>  kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
>  insert_work+0x48/0x370 kernel/workqueue.c:1332
>  __queue_work+0x5c1/0xed0 kernel/workqueue.c:1498
>  queue_work_on+0xee/0x110 kernel/workqueue.c:1525
>  queue_work include/linux/workqueue.h:507 [inline]
>  io_ring_ctx_wait_and_kill+0x30a/0x3c0 fs/io_uring.c:8914
>  io_uring_release+0x3e/0x50 fs/io_uring.c:8922
>  __fput+0x288/0x920 fs/file_table.c:280
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:164
>  exit_task_work include/linux/task_work.h:32 [inline]
>  do_exit+0xbae/0x2a30 kernel/exit.c:825
>  do_group_exit+0x125/0x310 kernel/exit.c:922
>  get_signal+0x47f/0x2160 kernel/signal.c:2808
>  arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:865
>  handle_signal_work kernel/entry/common.c:148 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
>  exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:209
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
>  do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> The buggy address belongs to the object at ffff888029d66000
>  which belongs to the cache kmalloc-4k of size 4096
> The buggy address is located 856 bytes inside of
>  4096-byte region [ffff888029d66000, ffff888029d67000)
> The buggy address belongs to the page:
> page:ffffea0000a75800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29d60
> head:ffffea0000a75800 order:3 compound_mapcount:0 compound_pincount:0
> flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888010842140
> raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> page_owner tracks the page as allocated
> page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6467, ts 58396905717, free_ts 57689976074
>  prep_new_page mm/page_alloc.c:2436 [inline]
>  get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4169
>  __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5391
>  alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
>  alloc_slab_page mm/slub.c:1688 [inline]
>  allocate_slab+0x32e/0x4b0 mm/slub.c:1828
>  new_slab mm/slub.c:1891 [inline]
>  new_slab_objects mm/slub.c:2637 [inline]
>  ___slab_alloc+0x4ba/0x820 mm/slub.c:2800
>  __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2840
>  slab_alloc_node mm/slub.c:2922 [inline]
>  slab_alloc mm/slub.c:2964 [inline]
>  __kmalloc+0x312/0x330 mm/slub.c:4108
>  kmalloc include/linux/slab.h:596 [inline]
>  tomoyo_realpath_from_path+0xc3/0x620 security/tomoyo/realpath.c:254
>  tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
>  tomoyo_path_perm+0x21b/0x400 security/tomoyo/file.c:822
>  security_inode_getattr+0xcf/0x140 security/security.c:1332
>  vfs_getattr fs/stat.c:139 [inline]
>  vfs_statx+0x164/0x390 fs/stat.c:207
>  vfs_fstatat fs/stat.c:225 [inline]
>  vfs_lstat include/linux/fs.h:3386 [inline]
>  __do_sys_newlstat+0x91/0x110 fs/stat.c:380
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> page last free stack trace:
>  reset_page_owner include/linux/page_owner.h:24 [inline]
>  free_pages_prepare mm/page_alloc.c:1346 [inline]
>  free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1397
>  free_unref_page_prepare mm/page_alloc.c:3332 [inline]
>  free_unref_page+0x19/0x690 mm/page_alloc.c:3411
>  qlink_free mm/kasan/quarantine.c:146 [inline]
>  qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
>  kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
>  __kasan_slab_alloc+0x8e/0xa0 mm/kasan/common.c:444
>  kasan_slab_alloc include/linux/kasan.h:254 [inline]
>  slab_post_alloc_hook mm/slab.h:519 [inline]
>  slab_alloc_node mm/slub.c:2956 [inline]
>  slab_alloc mm/slub.c:2964 [inline]
>  kmem_cache_alloc+0x285/0x4a0 mm/slub.c:2969
>  getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
>  getname_flags include/linux/audit.h:319 [inline]
>  getname+0x8e/0xd0 fs/namei.c:209
>  do_sys_openat2+0xf5/0x420 fs/open.c:1198
>  do_sys_open fs/open.c:1220 [inline]
>  __do_sys_open fs/open.c:1228 [inline]
>  __se_sys_open fs/open.c:1224 [inline]
>  __x64_sys_open+0x119/0x1c0 fs/open.c:1224
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> Memory state around the buggy address:
>  ffff888029d66200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888029d66280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff888029d66300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                                     ^
>  ffff888029d66380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888029d66400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
> 
> 
> Tested on:
> 
> commit:         bdd748b6 io-wq: move nr_running and worker_refs out of..
> git tree:       git://git.kernel.dk/linux-block for-5.15/io_uring
> console output: https://syzkaller.appspot.com/x/log.txt?x=13141b61300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cb4282936412304f
> dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
  2021-08-19 11:13     ` Pavel Begunkov
@ 2021-08-19 17:25       ` syzbot
  2021-08-19 20:56         ` Pavel Begunkov
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2021-08-19 17:25 UTC (permalink / raw)
  To: asml.silence, axboe, io-uring, linux-kernel, syzkaller-bugs

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+9c3492b27d10dc49ffa6@syzkaller.appspotmail.com

Tested on:

commit:         923ffe35 Revert "io_uring: improve tctx_task_work() ct..
git tree:       https://github.com/isilence/linux.git syztest_ctx_tw
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb4282936412304f
dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] KASAN: use-after-free Read in tctx_task_work (2)
  2021-08-19 17:25       ` syzbot
@ 2021-08-19 20:56         ` Pavel Begunkov
  0 siblings, 0 replies; 6+ messages in thread
From: Pavel Begunkov @ 2021-08-19 20:56 UTC (permalink / raw)
  To: syzbot, axboe, io-uring, linux-kernel, syzkaller-bugs

On 8/19/21 6:25 PM, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch and the reproducer did not trigger any issue

https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/io_uring&id=84a8ffdcd42da1f0710819e863a7db4309d4ceac

Ok, looks this patch broke it. I need to look where I'm wrong,
but for now it should be dropped. 

> 
> Reported-and-tested-by: syzbot+9c3492b27d10dc49ffa6@syzkaller.appspotmail.com
> 
> Tested on:
> 
> commit:         923ffe35 Revert "io_uring: improve tctx_task_work() ct..
> git tree:       https://github.com/isilence/linux.git syztest_ctx_tw
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cb4282936412304f
> dashboard link: https://syzkaller.appspot.com/bug?extid=9c3492b27d10dc49ffa6
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> 
> Note: testing is done by a robot and is best-effort only.
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-08-19 20:57 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-19  8:10 [syzbot] KASAN: use-after-free Read in tctx_task_work (2) syzbot
2021-08-19 10:03 ` Pavel Begunkov
2021-08-19 10:44   ` syzbot
2021-08-19 11:13     ` Pavel Begunkov
2021-08-19 17:25       ` syzbot
2021-08-19 20:56         ` Pavel Begunkov

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