linux-kernel - [syzbot] [v9fs?] KCSAN: data-race in p9_conn_cancel / p9_write

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Message-ID: <67abaeec.050a0220.3d72c.0087.GAE@google.com>
Date: Tue, 11 Feb 2025 12:11:24 -0800
From: syzbot <syzbot+d69a7cc8c683c2cb7506@...kaller.appspotmail.com>
To: asmadeus@...ewreck.org, ericvh@...nel.org, linux-kernel@...r.kernel.org, 
	linux_oss@...debyte.com, lucho@...kov.net, syzkaller-bugs@...glegroups.com, 
	v9fs@...ts.linux.dev
Subject: [syzbot] [v9fs?] KCSAN: data-race in p9_conn_cancel / p9_write_work (7)

Hello,

syzbot found the following issue on:

HEAD commit:    febbc555cf0f Merge tag 'nfsd-6.14-1' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=114123f8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7722a092753bcf03
dashboard link: https://syzkaller.appspot.com/bug?extid=d69a7cc8c683c2cb7506
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/34e7d4c83286/disk-febbc555.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483282168b02/vmlinux-febbc555.xz
kernel image: https://storage.googleapis.com/syzbot-assets/510fcf6f96a7/bzImage-febbc555.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d69a7cc8c683c2cb7506@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in p9_conn_cancel / p9_write_work

write to 0xffff88810db66428 of 4 bytes by task 23357 on cpu 1:
 p9_conn_cancel+0x89/0x400 net/9p/trans_fd.c:199
 p9_poll_mux net/9p/trans_fd.c:631 [inline]
 p9_poll_workfn+0x133/0x410 net/9p/trans_fd.c:1177
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff88810db66428 of 4 bytes by task 23378 on cpu 0:
 p9_write_work+0x26/0x750 net/9p/trans_fd.c:453
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000000 -> 0xffffff98

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 23378 Comm: kworker/0:8 Tainted: G        W          6.14.0-rc2-syzkaller-00034-gfebbc555cf0f #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: events p9_write_work
==================================================================


---
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