bisecting fixing commit since e0f8b8a65a473a8baa439cf865a694bbeb83fe90
building syzkaller on 5be3a391ba78f7f11b725cee6783880974b9895a
testing commit e0f8b8a65a473a8baa439cf865a694bbeb83fe90 with gcc (GCC) 8.1.0
kernel signature: 369bf539b105473478c922980680ca535b78d4170a3e8a03673d1e08ccb862ee
run #0: crashed: general protection fault in kobject_uevent
run #1: OK
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing current HEAD c10b57a567e4333b9fdf60b5ec36de9859263ca2
testing commit c10b57a567e4333b9fdf60b5ec36de9859263ca2 with gcc (GCC) 8.1.0
kernel signature: 6b1c94161eb1b3b52e5882373da2fe8804e8520b041c6b75d97ce3e01b90f7d4
run #0: crashed: general protection fault in kobject_uevent
run #1: OK
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
revisions tested: 2, total time: 38m40.511328331s (build: 17m36.254702142s, test: 19m45.673130621s)
the crash still happens on HEAD
commit msg: Linux 4.14.176
crash: general protection fault in kobject_uevent
random: 7 urandom warning(s) missed due to ratelimiting
FAT-fs (loop0): bogus number of reserved sectors
FAT-fs (loop0): Can't find a valid FAT filesystem
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 3633 Comm: systemd-udevd Not tainted 4.14.176-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808f91c580 task.stack: ffff88808f920000
RIP: 0010:kobject_uevent_env+0x93/0xb60 lib/kobject_uevent.c:355
RSP: 0018:ffff88808f927b78 EFLAGS: 00010206
RAX: 0000000000000018 RBX: 00000000000000a0 RCX: 1ffff11011f239be
RDX: 1ffffffff0edf53a RSI: 0000000000000002 RDI: 00000000000000c0
RBP: ffff88808f927c08 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000078 R11: ffff88808f91c580 R12: ffff88808cfe87c0
R13: dffffc0000000000 R14: 00000000000000a0 R15: ffff88808ae730a8
FS:  00007fa2fe6018c0(0000) GS:ffff8880aec00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000004 CR3: 000000008f60f000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 kobject_uevent+0xb/0x10 lib/kobject_uevent.c:553
 loop_clr_fd+0x492/0xac0 drivers/block/loop.c:1069
 __lo_release drivers/block/loop.c:1660 [inline]
 lo_release+0xe7/0x180 drivers/block/loop.c:1678
 __blkdev_put+0x406/0x730 fs/block_dev.c:1791
 blkdev_put+0x73/0x480 fs/block_dev.c:1856
 blkdev_close+0x88/0xd0 fs/block_dev.c:1863
 __fput+0x232/0x750 fs/file_table.c:210
 ____fput+0x9/0x10 fs/file_table.c:244
 task_work_run+0xe5/0x170 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x16a/0x1b0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7fa2fd748270
RSP: 002b:00007ffe616d2ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007ffe616d2d80 RCX: 00007fa2fd748270
RDX: 0000000000000000 RSI: 000000000000125f RDI: 000000000000000e
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe616d2e90
R13: 00005603cd744a60 R14: 00005603cde02dd0 R15: 00007ffe616d2d60
Code: 18 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 50 09 00 00 48 8b 5b 18 48 85 db 0f 84 d6 01 00 00 48 8d 7b 20 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 23 09 00 00 4c 8b 63 20 4d 85 e4 74 be 4d 
RIP: kobject_uevent_env+0x93/0xb60 lib/kobject_uevent.c:355 RSP: ffff88808f927b78
---[ end trace d6ad771a7e094ee7 ]---