syzbot


general protection fault in ep_poll_callback

Status: upstream: reported C repro on 2023/07/20 11:38
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+c2b68bdf76e442836443@syzkaller.appspotmail.com
First crash: 229d, last: 65d
Cause bisection: introduced by (bisect log) :
commit a0b0fd53e1e67639b303b15939b9c653dbe7a8c4
Author: Bart Van Assche <bvanassche@acm.org>
Date: Thu Feb 14 23:00:46 2019 +0000

  locking/lockdep: Free lock classes that are no longer in use

Crash: kernel BUG in ext4_mb_find_by_goal (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) [merge commit]:
commit 8c9440fea77440772542d6dbcb5c36182495c164
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon Jan 8 18:57:34 2024 +0000

  Merge tag 'vfs-6.8.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] general protection fault in ep_poll_callback 1 (3) 2023/07/21 09:47
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: wild-memory-access Read in ep_poll_callback fs 2 451d 465d 0/26 auto-obsoleted due to no activity on 2023/03/10 02:58
Last patch testing requests (1)
Created Duration User Patch Repo Result
2023/08/23 14:01 17m retest repro upstream report log
Fix bisection attempts (5)
Created Duration User Patch Repo Result
2024/02/17 00:33 10h21m bisect fix upstream job log (1)
2023/12/30 20:04 4h21m bisect fix upstream job log (0) log
2023/11/30 16:28 3h01m bisect fix upstream job log (0) log
2023/10/31 05:02 2h41m bisect fix upstream job log (0) log
2023/09/29 06:00 2h36m bisect fix upstream job log (0) log

Sample crash report:
general protection fault, maybe for address 0xffffc90003e0fdc8: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4473 Comm: udevd Not tainted 6.5.0-rc2-syzkaller-00052-gbfa3037d8280 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
RIP: 0010:__wake_up_common+0x13c/0x5a0 kernel/sched/wait.c:107
Code: c6 04 75 6e 49 8d 78 10 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 1c 03 00 00 48 8b 4c 24 08 4c 89 c7 8b 54 24 10 8b 74 24 04 <41> ff 50 10 85 c0 78 2d 74 11 41 83 e6 01 74 0b 83 6c 24 14 01 0f
RSP: 0018:ffffc900031cf790 EFLAGS: 00010046
RAX: 1ffff920007c1fb9 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffc90003e0fdb8
RBP: ffff8880273470d0 R08: ffffc90003e0fdb8 R09: ffffc900031cf830
R10: 0000000000000003 R11: 0000000000094000 R12: ffffc900031cf830
R13: dffffc0000000000 R14: 00000000ffff8880 R15: 816f3352ffff8868
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000fffffffe CR3: 000000000c776000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 __wake_up_common_lock+0xd6/0x140 kernel/sched/wait.c:138
 ep_poll_callback+0x316/0xc10 fs/eventpoll.c:1242
 __wake_up_common+0x140/0x5a0 kernel/sched/wait.c:107
 __wake_up_common_lock+0xd6/0x140 kernel/sched/wait.c:138
 signalfd_notify include/linux/signalfd.h:22 [inline]
 __send_signal_locked+0x94b/0x11d0 kernel/signal.c:1173
 do_send_sig_info kernel/signal.c:1296 [inline]
 group_send_sig_info+0x2ad/0x310 kernel/signal.c:1446
 forget_original_parent kernel/exit.c:709 [inline]
 exit_notify kernel/exit.c:734 [inline]
 do_exit+0xd9d/0x2a20 kernel/exit.c:894
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
 get_signal+0x23ea/0x2770 kernel/signal.c:2877
 arch_do_signal_or_restart+0x89/0x5f0 arch/x86/kernel/signal.c:308
 exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
 exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
 do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8fae30e3cd
Code: Unable to access opcode bytes at 0x7f8fae30e3a3.
RSP: 002b:00007ffea9c17ff0 EFLAGS: 00000246 ORIG_RAX: 00000000000000ea
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f8fae30e3cd
RDX: 0000000000000006 RSI: 0000000000001179 RDI: 0000000000001179
RBP: 0000000000001179 R08: 0000000000000000 R09: 0000000000000002
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000006
R13: 00007ffea9c18200 R14: 0000000000001000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__wake_up_common+0x13c/0x5a0 kernel/sched/wait.c:107
Code: c6 04 75 6e 49 8d 78 10 48 89 f8 48 c1 e8 03 42 80 3c 28 00 0f 85 1c 03 00 00 48 8b 4c 24 08 4c 89 c7 8b 54 24 10 8b 74 24 04 <41> ff 50 10 85 c0 78 2d 74 11 41 83 e6 01 74 0b 83 6c 24 14 01 0f
RSP: 0018:ffffc900031cf790 EFLAGS: 00010046

RAX: 1ffff920007c1fb9 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffc90003e0fdb8
RBP: ffff8880273470d0 R08: ffffc90003e0fdb8 R09: ffffc900031cf830
R10: 0000000000000003 R11: 0000000000094000 R12: ffffc900031cf830
R13: dffffc0000000000 R14: 00000000ffff8880 R15: 816f3352ffff8868
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000fffffffe CR3: 000000000c776000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
   0:	c6 04 75 6e 49 8d 78 	movb   $0x10,0x788d496e(,%rsi,2)
   7:	10
   8:	48 89 f8             	mov    %rdi,%rax
   b:	48 c1 e8 03          	shr    $0x3,%rax
   f:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
  14:	0f 85 1c 03 00 00    	jne    0x336
  1a:	48 8b 4c 24 08       	mov    0x8(%rsp),%rcx
  1f:	4c 89 c7             	mov    %r8,%rdi
  22:	8b 54 24 10          	mov    0x10(%rsp),%edx
  26:	8b 74 24 04          	mov    0x4(%rsp),%esi
* 2a:	41 ff 50 10          	call   *0x10(%r8) <-- trapping instruction
  2e:	85 c0                	test   %eax,%eax
  30:	78 2d                	js     0x5f
  32:	74 11                	je     0x45
  34:	41 83 e6 01          	and    $0x1,%r14d
  38:	74 0b                	je     0x45
  3a:	83 6c 24 14 01       	subl   $0x1,0x14(%rsp)
  3f:	0f                   	.byte 0xf

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/20 08:23 upstream bfa3037d8280 4547cdf9 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-badwrites-root general protection fault in ep_poll_callback
* Struck through repros no longer work on HEAD.