Hello, syzbot found the following issue on: HEAD commit: 5631c5e0 Merge tag 'xfs-5.9-merge-7' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15c21934900000 kernel config: https://syzkaller.appspot.com/x/.config?x=afba7c06f91e56eb dashboard link: https://syzkaller.appspot.com/bug?extid=452e9465a3b2817fa4c2 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=131e96aa900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+452e9465a3b2817fa4c2@xxxxxxxxxxxxxxxxxxxxxxxxx ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_write include/linux/instrumented.h:71 [inline] BUG: KASAN: null-ptr-deref in atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline] BUG: KASAN: null-ptr-deref in refcount_sub_and_test include/linux/refcount.h:266 [inline] BUG: KASAN: null-ptr-deref in refcount_dec_and_test include/linux/refcount.h:294 [inline] BUG: KASAN: null-ptr-deref in kref_put include/linux/kref.h:64 [inline] BUG: KASAN: null-ptr-deref in l2cap_chan_put+0x28/0x230 net/bluetooth/l2cap_core.c:502 Write of size 4 at addr 0000000000000018 by task kworker/0:1/7077 CPU: 0 PID: 7077 Comm: kworker/0:1 Not tainted 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events l2cap_chan_timeout Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 __kasan_report mm/kasan/report.c:517 [inline] kasan_report.cold+0x5/0x37 mm/kasan/report.c:530 check_memory_region_inline mm/kasan/generic.c:186 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 instrument_atomic_write include/linux/instrumented.h:71 [inline] atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline] refcount_sub_and_test include/linux/refcount.h:266 [inline] refcount_dec_and_test include/linux/refcount.h:294 [inline] kref_put include/linux/kref.h:64 [inline] l2cap_chan_put+0x28/0x230 net/bluetooth/l2cap_core.c:502 l2cap_sock_kill+0xbd/0x180 net/bluetooth/l2cap_sock.c:1217 l2cap_chan_timeout+0x1c1/0x450 net/bluetooth/l2cap_core.c:438 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 ================================================================== Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7077 Comm: kworker/0:1 Tainted: G B 5.8.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events l2cap_chan_timeout Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:231 end_report+0x4d/0x53 mm/kasan/report.c:104 __kasan_report mm/kasan/report.c:520 [inline] kasan_report.cold+0xd/0x37 mm/kasan/report.c:530 check_memory_region_inline mm/kasan/generic.c:186 [inline] check_memory_region+0x13d/0x180 mm/kasan/generic.c:192 instrument_atomic_write include/linux/instrumented.h:71 [inline] atomic_fetch_sub_release include/asm-generic/atomic-instrumented.h:220 [inline] refcount_sub_and_test include/linux/refcount.h:266 [inline] refcount_dec_and_test include/linux/refcount.h:294 [inline] kref_put include/linux/kref.h:64 [inline] l2cap_chan_put+0x28/0x230 net/bluetooth/l2cap_core.c:502 l2cap_sock_kill+0xbd/0x180 net/bluetooth/l2cap_sock.c:1217 l2cap_chan_timeout+0x1c1/0x450 net/bluetooth/l2cap_core.c:438 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 Kernel Offset: disabled Rebooting in 86400 seconds.. --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
