linux-kernel - [syzbot] [v9fs?] KCSAN: data-race in p9_conn_cancel / p9_poll

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Message-ID: <67a60b2b.050a0220.2b1e6.0026.GAE@google.com>
Date: Fri, 07 Feb 2025 05:31:23 -0800
From: syzbot <syzbot+483d6c9b9231ea7e1851@...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_poll_workfn (9)

Hello,

syzbot found the following issue on:

HEAD commit:    bb066fe812d6 Merge tag 'pci-v6.14-fixes-2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=167e64a4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9e757e3762bd630b
dashboard link: https://syzkaller.appspot.com/bug?extid=483d6c9b9231ea7e1851
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/96c2fa324092/disk-bb066fe8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d0c48f9198dc/vmlinux-bb066fe8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9ae4ace7c1c/bzImage-bb066fe8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+483d6c9b9231ea7e1851@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in p9_conn_cancel / p9_poll_workfn

write to 0xffff888164f81828 of 4 bytes by task 4264 on cpu 1:
 p9_conn_cancel+0x89/0x400 net/9p/trans_fd.c:199
 p9_write_work+0x3ac/0x750 net/9p/trans_fd.c:522
 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 0xffff888164f81828 of 4 bytes by task 9 on cpu 0:
 p9_poll_mux net/9p/trans_fd.c:625 [inline]
 p9_poll_workfn+0xc0/0x410 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

value changed: 0x00000000 -> 0xffffffe0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.14.0-rc1-syzkaller-00081-gbb066fe812d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: events p9_poll_workfn
==================================================================


---
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