syzbot


general protection fault in __ext4_journal_get_write_access (3)

Status: upstream: reported on 2025/07/21 07:49
Reported-by: syzbot+9a2e9ce19d0ec929e91b@syzkaller.appspotmail.com
First crash: 6d17h, last: 6d17h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 general protection fault in __ext4_journal_get_write_access (2) 2 1 172d 172d 0/3 auto-obsoleted due to no activity on 2025/05/16 06:11
upstream general protection fault in __ext4_journal_get_write_access fuse ext4 2 C done done 7 1720d 1769d 22/29 fixed on 2022/11/15 22:34
linux-6.1 general protection fault in __ext4_journal_get_write_access 2 2 315d 318d 0/3 auto-obsoleted due to no activity on 2024/12/24 15:34
android-6-1 general protection fault in __ext4_journal_get_write_access origin:lts missing-backport 2 syz 87 10d 495d 0/2 premoderation: reported syz repro on 2024/03/19 01:39

Sample crash report:
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: writeback.
general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 1 PID: 4522 Comm: syz.0.41 Not tainted 6.1.146-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__ext4_journal_get_write_access+0xc6/0x6d0 fs/ext4/ext4_jbd2.c:231
Code: 31 c0 49 8d 5f 30 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 d8 96 b5 ff 48 8b 1b 48 83 c3 38 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 bb 96 b5 ff 4c 8b 23 4d 85 e4 4c
RSP: 0018:ffffc90004bef880 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 0000000000000038 RCX: 3d6bc75ecdc55d00
RDX: ffff88802f189dc0 RSI: ffffffff8a8c15e0 RDI: ffffffff8adef260
RBP: ffffc90004bef950 R08: ffff8880553abbc8 R09: 0000000000000001
R10: fffffbfff1c3e91e R11: 1ffffffff1c3e91d R12: ffff888027744000
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880553abbc8
FS:  00007faecb1e06c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa40e07b9c8 CR3: 0000000018e8f000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_update_primary_sb fs/ext4/ioctl.c:67 [inline]
 ext4_update_superblocks_fn+0x25e/0xf20 fs/ext4/ioctl.c:221
 ext4_fill_super+0x29ee/0x8110 fs/ext4/super.c:5685
 get_tree_bdev+0x3f1/0x610 fs/super.c:1366
 vfs_get_tree+0x88/0x270 fs/super.c:1573
 do_new_mount+0x24a/0xa40 fs/namespace.c:3058
 do_mount fs/namespace.c:3401 [inline]
 __do_sys_mount fs/namespace.c:3609 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3586
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faeca39014a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007faecb1dfe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007faecb1dfef0 RCX: 00007faeca39014a
RDX: 0000200000000140 RSI: 0000200000000040 RDI: 00007faecb1dfeb0
RBP: 0000200000000140 R08: 00007faecb1dfef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000040
R13: 00007faecb1dfeb0 R14: 00000000000005fc R15: 0000200000000080
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__ext4_journal_get_write_access+0xc6/0x6d0 fs/ext4/ext4_jbd2.c:231
Code: 31 c0 49 8d 5f 30 48 89 d8 48 c1 e8 03 42 80 3c 28 00 74 08 48 89 df e8 d8 96 b5 ff 48 8b 1b 48 83 c3 38 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 bb 96 b5 ff 4c 8b 23 4d 85 e4 4c
RSP: 0018:ffffc90004bef880 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 0000000000000038 RCX: 3d6bc75ecdc55d00
RDX: ffff88802f189dc0 RSI: ffffffff8a8c15e0 RDI: ffffffff8adef260
RBP: ffffc90004bef950 R08: ffff8880553abbc8 R09: 0000000000000001
R10: fffffbfff1c3e91e R11: 1ffffffff1c3e91d R12: ffff888027744000
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880553abbc8
FS:  00007faecb1e06c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe130d83178 CR3: 0000000018e8f000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	31 c0                	xor    %eax,%eax
   2:	49 8d 5f 30          	lea    0x30(%r15),%rbx
   6:	48 89 d8             	mov    %rbx,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 d8 96 b5 ff       	call   0xffb596f4
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	48 83 c3 38          	add    $0x38,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 bb 96 b5 ff       	call   0xffb596f4
  39:	4c 8b 23             	mov    (%rbx),%r12
  3c:	4d 85 e4             	test   %r12,%r12
  3f:	4c                   	rex.WR

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/21 07:49 linux-6.1.y 3369c6df2fae 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in __ext4_journal_get_write_access
* Struck through repros no longer work on HEAD.