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* KASAN: use-after-free Write in process_preds
@ 2018-05-04  5:30 syzbot
  2018-05-04  5:36 ` Dmitry Vyukov
  0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2018-05-04  5:30 UTC (permalink / raw)
  To: linux-kernel, mingo, rostedt, syzkaller-bugs


syzbot found the following crash on:

HEAD commit:    03f5781be2c7 bpf, x86_32: add eBPF JIT compiler for ia32
git tree:       bpf-next
console output:
kernel config:
dashboard link:
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:

BUG: KASAN: use-after-free in predicate_parse  
kernel/trace/trace_events_filter.c:557 [inline]
BUG: KASAN: use-after-free in process_preds+0x1958/0x19b0  
Write of size 4 at addr ffff8801ada34ff0 by task syz-executor3/6458

CPU: 0 PID: 6458 Comm: syz-executor3 Not tainted 4.17.0-rc2+ #22
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x1b9/0x294 lib/dump_stack.c:113
  print_address_description+0x6c/0x20b mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
  __asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:437
  predicate_parse kernel/trace/trace_events_filter.c:557 [inline]
  process_preds+0x1958/0x19b0 kernel/trace/trace_events_filter.c:1505
  create_filter+0x155/0x270 kernel/trace/trace_events_filter.c:1713
  perf_event_set_filter+0x248/0x1230 kernel/events/core.c:9079
  _perf_ioctl+0x84c/0x15e0 kernel/events/core.c:5059
  perf_ioctl+0x59/0x80 kernel/events/core.c:5110
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:500 [inline]
  do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
  __do_sys_ioctl fs/ioctl.c:708 [inline]
  __se_sys_ioctl fs/ioctl.c:706 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
RIP: 0033:0x455979
RSP: 002b:00007fd67f515c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd67f5166d4 RCX: 0000000000455979
RDX: 0000000020000040 RSI: 0000000040082406 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000002bf R14: 00000000006f8288 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006b68d00 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffff8801daf2fcd8 ffffea0006a5d9e0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801ada34e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
  ffff8801ada34f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> ffff8801ada34f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
  ffff8801ada35000: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
  ffff8801ada35080: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc

This bug is generated by a bot. It may contain errors.
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syzbot engineers can be reached at

syzbot will keep track of this bug report.
If you forgot to add the Reported-by tag, once the fix for this bug is  
into any tree, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug  
Note: all commands must start from beginning of the line in the email body.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2018-05-04  5:30 KASAN: use-after-free Write in process_preds syzbot
2018-05-04  5:36 ` Dmitry Vyukov

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