[moderation] [scsi?] KCSAN: data-race in sg_common_write / sg_finish_rem_req (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e53642b87a4f Merge tag 'v6.18-rc3-smb-server-fixes' of git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17061fe2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d2e0bc0ae94545f7
dashboard link: https://syzkaller.appspot.com/bug?extid=3fd8cb6e827442a26422
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [James.B...@HansenPartnership.com dgil...@interlog.com linux-...@vger.kernel.org linux...@vger.kernel.org martin....@oracle.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/11dffeeb809f/disk-e53642b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c9676883f34a/vmlinux-e53642b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ae88632bdb7f/bzImage-e53642b8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fd8cb...@syzkaller.appspotmail.com

netlink: 8 bytes leftover after parsing attributes in process `syz.8.4930'.
==================================================================
BUG: KCSAN: data-race in sg_common_write / sg_finish_rem_req

write to 0xffff888119c4931d of 1 bytes by task 16624 on cpu 1:
sg_unlink_reserve drivers/scsi/sg.c:2059 [inline]
sg_finish_rem_req+0x11f/0x270 drivers/scsi/sg.c:1841
sg_rq_end_io_usercontext+0x38/0x1c0 drivers/scsi/sg.c:1301
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
worker_thread+0x582/0x770 kernel/workqueue.c:3427
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888119c4931d of 1 bytes by task 21531 on cpu 0:
sg_start_req drivers/scsi/sg.c:1781 [inline]
sg_common_write+0x961/0xc30 drivers/scsi/sg.c:799
sg_new_write+0x7b6/0x890 drivers/scsi/sg.c:766
sg_ioctl_common drivers/scsi/sg.c:931 [inline]
sg_ioctl+0xb81/0x1360 drivers/scsi/sg.c:1156
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
x64_sys_call+0x1816/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21531 Comm: syz.8.4930 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================


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