bisecting fixing commit since f8788d86ab28f61f7b46eb6be375f8a726783636
building syzkaller on 59b57593586656c1d5be820aeed0e751087e6ac6
testing commit f8788d86ab28f61f7b46eb6be375f8a726783636 with gcc (GCC) 8.1.0
kernel signature: 1079188d2a09f16859452ff5a89987344c522a52a5d75077c8bb4905e4eb1390
run #0: crashed: WARNING: refcount bug in l2cap_chan_put
run #1: crashed: WARNING: refcount bug in l2cap_chan_put
run #2: crashed: WARNING: refcount bug in l2cap_chan_put
run #3: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #4: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #5: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #6: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #7: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #8: crashed: WARNING: refcount bug in l2cap_chan_put
run #9: crashed: KASAN: use-after-free Write in l2cap_chan_put
testing current HEAD b0c3ba31be3e45a130e13b278cf3b90f69bda6f6
testing commit b0c3ba31be3e45a130e13b278cf3b90f69bda6f6 with gcc (GCC) 8.1.0
kernel signature: f0fdbacce4b22f687a2119b7211995154009b7f26a0d71692dd625608332257c
run #0: crashed: WARNING: refcount bug in l2cap_chan_put
run #1: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #2: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #3: crashed: WARNING: refcount bug in l2cap_chan_put
run #4: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #5: crashed: WARNING: refcount bug in l2cap_chan_put
run #6: crashed: KASAN: use-after-free Read in l2cap_chan_close
run #7: crashed: WARNING: refcount bug in l2cap_chan_put
run #8: boot failed: can't ssh into the instance
run #9: boot failed: can't ssh into the instance
revisions tested: 2, total time: 27m16.120311012s (build: 12m14.897703152s, test: 14m6.880084004s)
the crash still happens on HEAD
commit msg: Merge tag 'fsnotify_for_v5.7-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
crash: WARNING: refcount bug in l2cap_chan_put
IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 12 at lib/refcount.c:28 refcount_warn_saturate+0x135/0x140 lib/refcount.c:28
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.7.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events do_enable_set
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x12d/0x187 lib/dump_stack.c:118
 panic+0x22a/0x4e3 kernel/panic.c:221
 __warn.cold.10+0x25/0x2a kernel/panic.c:582
 report_bug+0x1b0/0x270 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x135/0x140 lib/refcount.c:28
Code: 20 df fd 0f 0b e9 51 ff ff ff 48 89 df e8 a3 74 41 fe e9 1f ff ff ff 48 c7 c7 20 34 0e 88 c6 05 e2 4f 98 06 01 e8 93 20 df fd <0f> 0b e9 2a ff ff ff 0f 1f 40 00 55 be 04 00 00 00 48 89 e5 41 57
RSP: 0018:ffffc90000d2fbf0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88808fdcf018 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffffff8adde120
RBP: ffffc90000d2fc00 R08: ffffed1015d466a9 R09: ffffed1015d466a9
R10: ffff8880aea33547 R11: ffffed1015d466a8 R12: 0000000000000003
R13: ffff888097c14c00 R14: 0000000000000000 R15: ffffc90000d2fe48
 refcount_sub_and_test include/linux/refcount.h:274 [inline]
 refcount_dec_and_test include/linux/refcount.h:294 [inline]
 kref_put include/linux/kref.h:64 [inline]
 l2cap_chan_put+0x175/0x1d0 net/bluetooth/l2cap_core.c:502
 do_enable_set+0x48a/0x8b0 net/bluetooth/6lowpan.c:1075
 process_one_work+0x893/0x1690 kernel/workqueue.c:2268
 worker_thread+0x85/0xb60 kernel/workqueue.c:2414
 kthread+0x354/0x420 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351
Kernel Offset: disabled
Rebooting in 86400 seconds..