[moderation] [scsi?] KCSAN: data-race in sg_fill_request_table / sg_rq_end_io

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 785cdec46e92 Merge tag 'x86-core-2025-05-25' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13546df4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=87a03daca3305eb8
dashboard link: https://syzkaller.appspot.com/bug?extid=c9d05b79ba1064aa8bc5
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
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/4c6123762320/disk-785cdec4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f1d27469862e/vmlinux-785cdec4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd1b3e656908/bzImage-785cdec4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c9d05b...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in sg_fill_request_table / sg_rq_end_io

write to 0xffff888146158111 of 1 bytes by interrupt on cpu 1:
sg_rq_end_io+0x1a2/0x740 drivers/scsi/sg.c:1349
__blk_mq_end_request+0x25d/0x350 block/blk-mq.c:1139
scsi_end_request+0x29c/0x4c0 drivers/scsi/scsi_lib.c:670
scsi_io_completion+0x7f/0x200 drivers/scsi/scsi_lib.c:1078
scsi_finish_command+0x1c7/0x1e0 drivers/scsi/scsi.c:198
scsi_complete+0xc3/0x1e0 drivers/scsi/scsi_lib.c:1547
blk_complete_reqs block/blk-mq.c:1224 [inline]
blk_done_softirq+0x77/0xb0 block/blk-mq.c:1229
handle_softirqs+0xb7/0x290 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x3a/0xc0 kernel/softirq.c:680
common_interrupt+0x83/0x90 arch/x86/kernel/irq.c:285
asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
kcsan_setup_watchpoint+0x415/0x430 kernel/kcsan/core.c:705
skb_end_pointer include/linux/skbuff.h:1681 [inline]
skb_release_data+0x41/0x4e0 net/core/skbuff.c:1076
skb_release_all net/core/skbuff.c:1162 [inline]
__kfree_skb+0x44/0x150 net/core/skbuff.c:1176
sk_skb_reason_drop+0xbd/0x270 net/core/skbuff.c:1214
kfree_skb_reason include/linux/skbuff.h:1279 [inline]
kfree_skb include/linux/skbuff.h:1288 [inline]
kauditd_hold_skb+0x101/0x1c0 kernel/audit.c:611
kauditd_send_queue+0x273/0x2c0 kernel/audit.c:766
kauditd_thread+0x421/0x630 kernel/audit.c:890
kthread+0x486/0x510 kernel/kthread.c:464
ret_from_fork+0x4e/0x60 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888146158111 of 1 bytes by task 9226 on cpu 0:
sg_fill_request_table+0x65/0x1e0 drivers/scsi/sg.c:865
sg_ioctl_common drivers/scsi/sg.c:1082 [inline]
sg_ioctl+0x6b1/0x1360 drivers/scsi/sg.c:1156
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:893
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd0/0x1b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9226 Comm: syz.3.2109 Not tainted 6.15.0-syzkaller-01958-g785cdec46e92 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

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