bisecting fixing commit since ddef1e8e3f6eb26034833b7255e3fa584d54a230
building syzkaller on af5c522d02400b35a930d6fbdf286f9ce2afc8ba
testing commit ddef1e8e3f6eb26034833b7255e3fa584d54a230 with gcc (GCC) 8.1.0
kernel signature: 5640edbe5a8a8c25d36507829196b7da844880f3
all runs: crashed: KASAN: use-after-free Read in relay_switch_subbuf
testing current HEAD bfb9e5c03076a446b1f4f6a523ddc8d723c907a6
testing commit bfb9e5c03076a446b1f4f6a523ddc8d723c907a6 with gcc (GCC) 8.1.0
kernel signature: 3a8c1780ac28d1d85e3210cb1d9941feb28bd034
run #0: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #1: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #2: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #3: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #4: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #5: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #6: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #7: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #8: crashed: KASAN: use-after-free Read in relay_switch_subbuf
run #9: crashed: general protection fault in relay_switch_subbuf
revisions tested: 2, total time: 23m40.00138701s (build: 16m35.4558679s, test: 6m21.36896042s)
the crash still happens on HEAD
commit msg: Linux 4.14.159
crash: general protection fault in relay_switch_subbuf
kasan: CONFIG_KASAN_INLINE enabled
devpts: called with bogus options
devpts: called with bogus options
devpts: called with bogus options
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
devpts: called with bogus options
Modules linked in:
CPU: 0 PID: 3 Comm: kworker/0:0 Not tainted 4.14.159-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events __blk_release_queue
devpts: called with bogus options
task: ffff8880a9c6c0c0 task.stack: ffff8880a9c78000
RIP: 0010:relay_switch_subbuf+0x1d4/0xc40 kernel/relay.c:754
RSP: 0018:ffff8880a9c7fb88 EFLAGS: 00010206
devpts: called with bogus options
RAX: dffffc0000000000 RBX: ffff8880820702c0 RCX: ffff888082070378
RDX: 000000000000000a RSI: ffff8880820702d8 RDI: 0000000000000050
RBP: ffff8880a9c7fbd8 R08: ffff8880820702d0 R09: ffff8880820702e8
R10: 1ffff1101040e06e R11: ffff8880a9c6c0c0 R12: ffff888086ece420
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc3e7322e8 CR3: 00000000a5aa5000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 relay_flush+0x183/0x230 kernel/relay.c:882
 blk_trace_startstop+0x40c/0x570 kernel/trace/blktrace.c:657
 blk_trace_shutdown+0x3a/0x50 kernel/trace/blktrace.c:727
 __blk_release_queue+0x1f9/0x470 block/blk-sysfs.c:830
 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2114
 worker_thread+0xcc/0xee0 kernel/workqueue.c:2248
 kthread+0x338/0x400 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 3b 09 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 6c 24 58 49 8d 7d 50 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 bb 08 00 00 48 ba 00 00 00 00 00 fc ff df 48 
RIP: relay_switch_subbuf+0x1d4/0xc40 kernel/relay.c:754 RSP: ffff8880a9c7fb88
---[ end trace 48471fc7a306cb09 ]---