[9p?] [net?] KCSAN: data-race in p9_conn_cancel / p9_fd_request (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0a71553536d2 Merge tag 'drm-fixes-2023-01-06' of git://ano..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=131be376480000
kernel config: https://syzkaller.appspot.com/x/.config?x=2af8d17d4736de61
dashboard link: https://syzkaller.appspot.com/bug?extid=359e0ffe8c835fe8b476
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [asma...@codewreck.org da...@davemloft.net edum...@google.com eri...@gmail.com ku...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@crudebyte.com lu...@ionkov.net net...@vger.kernel.org pab...@redhat.com v9fs-de...@lists.sourceforge.net]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/f78275fc6383/disk-0a715535.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b25c7851c71a/vmlinux-0a715535.xz
kernel image: https://storage.googleapis.com/syzbot-assets/41564a4e45b0/bzImage-0a715535.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+359e0f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in p9_conn_cancel / p9_fd_request

write to 0xffff888136659428 of 4 bytes by task 4048 on cpu 0:
p9_conn_cancel+0x89/0x440 net/9p/trans_fd.c:200
p9_poll_mux net/9p/trans_fd.c:632 [inline]
p9_poll_workfn+0x15c/0x420 net/9p/trans_fd.c:1167
process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
worker_thread+0x618/0xa70 kernel/workqueue.c:2436
kthread+0x1a9/0x1e0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

read to 0xffff888136659428 of 4 bytes by task 30956 on cpu 1:
p9_fd_request+0x2c/0x2b0 net/9p/trans_fd.c:674
p9_client_rpc+0x1c4/0x6e0 net/9p/client.c:697
p9_client_version+0xa4/0x310
p9_client_create+0x61b/0x7a0 net/9p/client.c:1026
v9fs_session_init+0x100/0xcf0 fs/9p/v9fs.c:407
v9fs_mount+0x78/0x660 fs/9p/vfs_super.c:125
legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
vfs_get_tree+0x49/0x190 fs/super.c:1489
do_new_mount+0x200/0x650 fs/namespace.c:3145
path_mount+0x4aa/0xb70 fs/namespace.c:3475
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3697 [inline]
__se_sys_mount+0x281/0x2d0 fs/namespace.c:3674
__x64_sys_mount+0x63/0x70 fs/namespace.c:3674
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0xffffff98

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 30956 Comm: syz-executor.5 Tainted: G W 6.2.0-rc2-syzkaller-00282-g0a71553536d2-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.