[syzbot] KASAN: null-ptr-deref Write in kcm_tx_work (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: df0cc57e057f Linux 5.16
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a89d2db00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ea1f52f5503d3ac3
dashboard link: https://syzkaller.appspot.com/bug?extid=25ca556057c68f8a03a2
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+25ca55...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:86 [inline]
BUG: KASAN: null-ptr-deref in clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
BUG: KASAN: null-ptr-deref in kcm_tx_work+0xff/0x160 net/kcm/kcmsock.c:741
Write of size 8 at addr 0000000000000008 by task kworker/u4:47/7955

CPU: 1 PID: 7955 Comm: kworker/u4:47 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kkcmd kcm_tx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
__kasan_report mm/kasan/report.c:437 [inline]
kasan_report.cold+0x66/0xdf mm/kasan/report.c:450
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
instrument_atomic_write include/linux/instrumented.h:86 [inline]
clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
kcm_tx_work+0xff/0x160 net/kcm/kcmsock.c:741
process_one_work+0x9b2/0x1660 kernel/workqueue.c:2298
worker_thread+0x65d/0x1130 kernel/workqueue.c:2445
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 7955 Comm: kworker/u4:47 Tainted: G B 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: kkcmd kcm_tx_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
panic+0x2b0/0x6dd kernel/panic.c:232
end_report.cold+0x63/0x6f mm/kasan/report.c:128
__kasan_report mm/kasan/report.c:440 [inline]
kasan_report.cold+0x71/0xdf mm/kasan/report.c:450
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
instrument_atomic_write include/linux/instrumented.h:86 [inline]
clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
kcm_tx_work+0xff/0x160 net/kcm/kcmsock.c:741
process_one_work+0x9b2/0x1660 kernel/workqueue.c:2298
worker_thread+0x65d/0x1130 kernel/workqueue.c:2445
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[syzbot]

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