From: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
To: Chuck Lever <cel@kernel.org>, Jeff Layton <jlayton@kernel.org>,
Trond Myklebust <trondmy@kernel.org>,
Anna Schumaker <anna@kernel.org>
Cc: Shuangpeng Bai <shuangpeng.kernel@gmail.com>,
linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [BUG] lockd: KASAN: slab-use-after-free in nlm_async_call
Date: Tue, 18 Aug 2026 19:58:06 -0400 [thread overview]
Message-ID: <20260818235808.3458075-1-shuangpeng.kernel@gmail.com> (raw)
Hi Kernel Maintainers,
I hit the following report while testing current upstream kernel:
KASAN: slab-use-after-free in nlm_async_call
on commit: 3aa1dcaa4f6f5ae08936491e08bd456f331f2d40 (2026-08-13)
To help trigger the bug more reliably, we applied a minimal diagnostic patch
that only adds delays and print statements.
The reproducer and .config files are here.
https://gist.github.com/shuangpengbai/e0569a211da5a1738fb91b1833465662
I'm happy to test debug patches or provide additional information.
Reported-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
[ 193.891339][ T8377] BUG: KASAN: slab-use-after-free in nlm_async_call+0xd6/0x230
[ 193.893522][ T8377] Read of size 8 at addr ffff88811b04c808 by task lockd/8377
[ 193.895154][ T8377]
[ 193.895574][ T8377] Call Trace:
[ 193.895578][ T8377] <TASK>
[ 193.895581][ T8377] dump_stack_lvl+0x26/0x80
[ 193.895592][ T8377] print_report+0x147/0x790
[ 193.895619][ T8377] kasan_report+0xc3/0x100
[ 193.895631][ T8377] nlm_async_call+0xd6/0x230
[ 193.895688][ T8377] nlmsvc_retry_blocked+0x61c/0x800
[ 193.895695][ T8377] lockd+0x144/0x1c0
[ 193.895702][ T8377] kthread+0x2f2/0x3c0
[ 193.895722][ T8377] ret_from_fork+0x27d/0x670
[ 193.895747][ T8377] ret_from_fork_asm+0x1a/0x30
[ 193.895754][ T8377] </TASK>
[ 193.913276][ T8377] Allocated by task 8377 on cpu 1 at 181.704904s:
[ 193.914652][ T8377] __kmalloc_cache_noprof+0x248/0x4b0
[ 193.915123][ T8377] nlm_alloc_call+0x4b/0x1b0
[ 193.915527][ T8377] nlmsvc_lock+0x3d2/0xfc0
[ 193.915922][ T8377] nlm4svc_do_lock+0x291/0x480
[ 193.916341][ T8377] nlmsvc_dispatch+0xac/0x1b0
[ 193.916752][ T8377] svc_process_common+0x1229/0x1700
[ 193.917211][ T8377] svc_process+0x26b/0x560
[ 193.917601][ T8377] svc_recv+0x1690/0x1c70
[ 193.917986][ T8377] lockd+0x14e/0x1c0
[ 193.919766][ T8377] Freed by task 8392 on cpu 1 at 192.290946s:
[ 193.921551][ T8377] kfree+0x134/0x450
[ 193.921895][ T8377] nlmsvc_release_block+0x231/0x290
[ 193.922345][ T8377] nlmsvc_traverse_blocks+0x139/0x1b0
[ 193.922816][ T8377] nlm_traverse_files+0x1aa/0xa00
[ 193.923250][ T8377] nlmsvc_free_host_resources+0x12/0x60
[ 193.923726][ T8377] nlm_shutdown_hosts_net+0x127/0x280
[ 193.924193][ T8377] lockd_down+0xd5/0x1c0
[ 193.924561][ T8377] nfsd_destroy_serv+0x265/0x400
[ 193.924994][ T8377] nfsd_shutdown_threads+0xbb/0x100
[ 193.925443][ T8377] nfsd_umount+0x3b/0xc0
[ 193.925815][ T8377] deactivate_locked_super+0x9c/0x230
[ 193.926279][ T8377] cleanup_mnt+0x3a8/0x420
Best,
Shuangpeng
reply other threads:[~2026-08-19 0:00 UTC|newest]
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