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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Hulk Robot <hulkci@huawei.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Yang Yingliang <yangyingliang@huawei.com>,
	Pavel Skripkin <paskripkin@gmail.com>, Tejun Heo <tj@kernel.org>
Subject: [PATCH 5.10 05/24] workqueue: fix UAF in pwq_unbound_release_workfn()
Date: Thu, 29 Jul 2021 15:54:25 +0200	[thread overview]
Message-ID: <20210729135137.441570428@linuxfoundation.org> (raw)
In-Reply-To: <20210729135137.267680390@linuxfoundation.org>

From: Yang Yingliang <yangyingliang@huawei.com>

commit b42b0bddcbc87b4c66f6497f66fc72d52b712aa7 upstream.

I got a UAF report when doing fuzz test:

[  152.880091][ T8030] ==================================================================
[  152.881240][ T8030] BUG: KASAN: use-after-free in pwq_unbound_release_workfn+0x50/0x190
[  152.882442][ T8030] Read of size 4 at addr ffff88810d31bd00 by task kworker/3:2/8030
[  152.883578][ T8030]
[  152.883932][ T8030] CPU: 3 PID: 8030 Comm: kworker/3:2 Not tainted 5.13.0+ #249
[  152.885014][ T8030] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[  152.886442][ T8030] Workqueue: events pwq_unbound_release_workfn
[  152.887358][ T8030] Call Trace:
[  152.887837][ T8030]  dump_stack_lvl+0x75/0x9b
[  152.888525][ T8030]  ? pwq_unbound_release_workfn+0x50/0x190
[  152.889371][ T8030]  print_address_description.constprop.10+0x48/0x70
[  152.890326][ T8030]  ? pwq_unbound_release_workfn+0x50/0x190
[  152.891163][ T8030]  ? pwq_unbound_release_workfn+0x50/0x190
[  152.891999][ T8030]  kasan_report.cold.15+0x82/0xdb
[  152.892740][ T8030]  ? pwq_unbound_release_workfn+0x50/0x190
[  152.893594][ T8030]  __asan_load4+0x69/0x90
[  152.894243][ T8030]  pwq_unbound_release_workfn+0x50/0x190
[  152.895057][ T8030]  process_one_work+0x47b/0x890
[  152.895778][ T8030]  worker_thread+0x5c/0x790
[  152.896439][ T8030]  ? process_one_work+0x890/0x890
[  152.897163][ T8030]  kthread+0x223/0x250
[  152.897747][ T8030]  ? set_kthread_struct+0xb0/0xb0
[  152.898471][ T8030]  ret_from_fork+0x1f/0x30
[  152.899114][ T8030]
[  152.899446][ T8030] Allocated by task 8884:
[  152.900084][ T8030]  kasan_save_stack+0x21/0x50
[  152.900769][ T8030]  __kasan_kmalloc+0x88/0xb0
[  152.901416][ T8030]  __kmalloc+0x29c/0x460
[  152.902014][ T8030]  alloc_workqueue+0x111/0x8e0
[  152.902690][ T8030]  __btrfs_alloc_workqueue+0x11e/0x2a0
[  152.903459][ T8030]  btrfs_alloc_workqueue+0x6d/0x1d0
[  152.904198][ T8030]  scrub_workers_get+0x1e8/0x490
[  152.904929][ T8030]  btrfs_scrub_dev+0x1b9/0x9c0
[  152.905599][ T8030]  btrfs_ioctl+0x122c/0x4e50
[  152.906247][ T8030]  __x64_sys_ioctl+0x137/0x190
[  152.906916][ T8030]  do_syscall_64+0x34/0xb0
[  152.907535][ T8030]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  152.908365][ T8030]
[  152.908688][ T8030] Freed by task 8884:
[  152.909243][ T8030]  kasan_save_stack+0x21/0x50
[  152.909893][ T8030]  kasan_set_track+0x20/0x30
[  152.910541][ T8030]  kasan_set_free_info+0x24/0x40
[  152.911265][ T8030]  __kasan_slab_free+0xf7/0x140
[  152.911964][ T8030]  kfree+0x9e/0x3d0
[  152.912501][ T8030]  alloc_workqueue+0x7d7/0x8e0
[  152.913182][ T8030]  __btrfs_alloc_workqueue+0x11e/0x2a0
[  152.913949][ T8030]  btrfs_alloc_workqueue+0x6d/0x1d0
[  152.914703][ T8030]  scrub_workers_get+0x1e8/0x490
[  152.915402][ T8030]  btrfs_scrub_dev+0x1b9/0x9c0
[  152.916077][ T8030]  btrfs_ioctl+0x122c/0x4e50
[  152.916729][ T8030]  __x64_sys_ioctl+0x137/0x190
[  152.917414][ T8030]  do_syscall_64+0x34/0xb0
[  152.918034][ T8030]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  152.918872][ T8030]
[  152.919203][ T8030] The buggy address belongs to the object at ffff88810d31bc00
[  152.919203][ T8030]  which belongs to the cache kmalloc-512 of size 512
[  152.921155][ T8030] The buggy address is located 256 bytes inside of
[  152.921155][ T8030]  512-byte region [ffff88810d31bc00, ffff88810d31be00)
[  152.922993][ T8030] The buggy address belongs to the page:
[  152.923800][ T8030] page:ffffea000434c600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10d318
[  152.925249][ T8030] head:ffffea000434c600 order:2 compound_mapcount:0 compound_pincount:0
[  152.926399][ T8030] flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
[  152.927515][ T8030] raw: 057ff00000010200 dead000000000100 dead000000000122 ffff888009c42c80
[  152.928716][ T8030] raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
[  152.929890][ T8030] page dumped because: kasan: bad access detected
[  152.930759][ T8030]
[  152.931076][ T8030] Memory state around the buggy address:
[  152.931851][ T8030]  ffff88810d31bc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  152.932967][ T8030]  ffff88810d31bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  152.934068][ T8030] >ffff88810d31bd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  152.935189][ T8030]                    ^
[  152.935763][ T8030]  ffff88810d31bd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  152.936847][ T8030]  ffff88810d31be00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  152.937940][ T8030] ==================================================================

If apply_wqattrs_prepare() fails in alloc_workqueue(), it will call put_pwq()
which invoke a work queue to call pwq_unbound_release_workfn() and use the 'wq'.
The 'wq' allocated in alloc_workqueue() will be freed in error path when
apply_wqattrs_prepare() fails. So it will lead a UAF.

CPU0                                          CPU1
alloc_workqueue()
alloc_and_link_pwqs()
apply_wqattrs_prepare() fails
apply_wqattrs_cleanup()
schedule_work(&pwq->unbound_release_work)
kfree(wq)
                                              worker_thread()
                                              pwq_unbound_release_workfn() <- trigger uaf here

If apply_wqattrs_prepare() fails, the new pwq are not linked, it doesn't
hold any reference to the 'wq', 'wq' is invalid to access in the worker,
so add check pwq if linked to fix this.

Fixes: 2d5f0764b526 ("workqueue: split apply_workqueue_attrs() into 3 stages")
Cc: stable@vger.kernel.org # v4.2+
Reported-by: Hulk Robot <hulkci@huawei.com>
Suggested-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Tested-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/workqueue.c |   20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3670,15 +3670,21 @@ static void pwq_unbound_release_workfn(s
 						  unbound_release_work);
 	struct workqueue_struct *wq = pwq->wq;
 	struct worker_pool *pool = pwq->pool;
-	bool is_last;
+	bool is_last = false;
 
-	if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
-		return;
+	/*
+	 * when @pwq is not linked, it doesn't hold any reference to the
+	 * @wq, and @wq is invalid to access.
+	 */
+	if (!list_empty(&pwq->pwqs_node)) {
+		if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
+			return;
 
-	mutex_lock(&wq->mutex);
-	list_del_rcu(&pwq->pwqs_node);
-	is_last = list_empty(&wq->pwqs);
-	mutex_unlock(&wq->mutex);
+		mutex_lock(&wq->mutex);
+		list_del_rcu(&pwq->pwqs_node);
+		is_last = list_empty(&wq->pwqs);
+		mutex_unlock(&wq->mutex);
+	}
 
 	mutex_lock(&wq_pool_mutex);
 	put_unbound_pool(pool);



  parent reply	other threads:[~2021-07-29 14:01 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 13:54 [PATCH 5.10 00/24] 5.10.55-rc1 review Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 01/24] tools: Allow proper CC/CXX/... override with LLVM=1 in Makefile.include Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 02/24] [PATCH] io_uring: fix link timeout refs Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 03/24] KVM: x86: determine if an exception has an error code only when injecting it Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 04/24] af_unix: fix garbage collect vs MSG_PEEK Greg Kroah-Hartman
2021-07-29 13:54 ` Greg Kroah-Hartman [this message]
2021-07-29 13:54 ` [PATCH 5.10 06/24] cgroup1: fix leaked context root causing sporadic NULL deref in LTP Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 07/24] net/802/mrp: fix memleak in mrp_request_join() Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 08/24] net/802/garp: fix memleak in garp_request_join() Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 09/24] net: annotate data race around sk_ll_usec Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 10/24] sctp: move 198 addresses from unusable to private scope Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 11/24] rcu-tasks: Dont delete holdouts within trc_inspect_reader() Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 12/24] rcu-tasks: Dont delete holdouts within trc_wait_for_one_reader() Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 13/24] ipv6: allocate enough headroom in ip6_finish_output2() Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 14/24] drm/ttm: add a check against null pointer dereference Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 15/24] hfs: add missing clean-up in hfs_fill_super Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 16/24] hfs: fix high memory mapping in hfs_bnode_read Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 17/24] hfs: add lock nesting notation to hfs_find_init Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 18/24] firmware: arm_scmi: Fix possible scmi_linux_errmap buffer overflow Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 19/24] firmware: arm_scmi: Fix range check for the maximum number of pending messages Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 20/24] cifs: fix the out of range assignment to bit fields in parse_server_interfaces Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 21/24] iomap: remove the length variable in iomap_seek_data Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 22/24] iomap: remove the length variable in iomap_seek_hole Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 23/24] ARM: dts: versatile: Fix up interrupt controller node names Greg Kroah-Hartman
2021-07-29 13:54 ` [PATCH 5.10 24/24] ipv6: ip6_finish_output2: set sk into newly allocated nskb Greg Kroah-Hartman
2021-07-29 19:47 ` [PATCH 5.10 00/24] 5.10.55-rc1 review Pavel Machek
2021-07-29 22:53 ` Shuah Khan
2021-07-30  4:58   ` Greg Kroah-Hartman
2021-07-29 23:36 ` Florian Fainelli
2021-07-30  2:40 ` Shuah Khan
2021-07-30  6:23 ` Naresh Kamboju
2021-07-30 10:12 ` Sudip Mukherjee
2021-07-31  4:43 ` Guenter Roeck
2021-07-31  7:51 ` Fox Chen

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