syzbot

 sign-in | mailing list | source | docs
🐞 Open [994] ≡ Subsystems 🐞 Fixed [5244] 🐞 Invalid [12516] ⬇ Missing Backports [83] 📈 Kernel Health 📈 Bug Lifetimes 📈 Fuzzing 📈 Crashes 💬 Send us feedback

kernel BUG in ext4_split_extent_at (2)

Status: fixed on 2024/01/30 15:47
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+0f4d9f68fb6632330c6c@syzkaller.appspotmail.com
Fix commit: 6f861765464f fs: Block writes to mounted block devices
First crash: 323d, last: 124d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: fixed by (bisect log) :
commit 6f861765464f43a71462d52026fbddfc858239a5
Author: Jan Kara <jack@suse.cz>
Date: Wed Nov 1 17:43:10 2023 +0000

  fs: Block writes to mounted block devices

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] kernel BUG in ext4_split_extent_at (2) 2 (5) 2024/01/25 12:55
▶ ▼ Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_split_extent_at ext4 1 809d 805d 0/26 auto-closed as invalid on 2022/06/08 01:32
android-5-10 kernel BUG in ext4_split_extent_at C error error 4 43d 323d 0/2 upstream: reported C repro on 2023/06/09 00:07
android-6-1 kernel BUG in ext4_split_extent_at origin:upstream missing-backport C error 1 7d15h 323d 0/2 upstream: reported C repro on 2023/06/09 05:14
android-5-15 kernel BUG in ext4_split_extent_at origin:upstream missing-backport syz error 1 7d21h 323d 0/2 premoderation: reported syz repro on 2023/06/09 01:17
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2023/12/25 03:20 24m retest repro upstream report log
2023/11/30 04:29 17m retest repro upstream report log
2023/11/16 00:46 17m retest repro upstream report log
2023/09/08 09:30 17m retest repro upstream report log
2023/08/25 00:57 29m retest repro upstream report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2024/01/24 13:39 5h41m bisect fix upstream job log (1)
2023/10/16 00:31 2h44m bisect fix upstream job log (0) log

Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/ext4_extents.h:200!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5885 Comm: syz-executor219 Not tainted 6.4.0-syzkaller-12365-g8689f4f2ea56 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
RIP: 0010:ext4_ext_mark_unwritten fs/ext4/ext4_extents.h:200 [inline]
RIP: 0010:ext4_split_extent_at+0xd11/0xe10 fs/ext4/extents.c:3221
Code: e9 d2 f8 ff ff e8 1f 6d 5d ff 66 81 c5 00 80 e9 32 fd ff ff e8 10 6d 5d ff 44 8d bd 00 80 ff ff e9 d1 fc ff ff e8 ff 6c 5d ff <0f> 0b 48 8b 7c 24 18 e8 73 9d b0 ff e9 7f f3 ff ff 48 89 cf e8 46
RSP: 0018:ffffc900055ef268 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88807d9c0000 RSI: ffffffff82277271 RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88807587d00c
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88807587d012
FS:  00007f4820ae9700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4820ae8fe8 CR3: 0000000028105000 CR4: 0000000000350ee0
Call Trace:
 <TASK>
 ext4_split_extent+0x3fc/0x530 fs/ext4/extents.c:3384
 ext4_ext_handle_unwritten_extents fs/ext4/extents.c:3874 [inline]
 ext4_ext_map_blocks+0x2e22/0x5bc0 fs/ext4/extents.c:4166
 ext4_map_blocks+0x760/0x1890 fs/ext4/inode.c:621
 ext4_iomap_alloc fs/ext4/inode.c:3276 [inline]
 ext4_iomap_begin+0x43d/0x7a0 fs/ext4/inode.c:3326
 iomap_iter+0x446/0x10e0 fs/iomap/iter.c:91
 __iomap_dio_rw+0x6e3/0x1d80 fs/iomap/direct-io.c:574
 iomap_dio_rw+0x40/0xa0 fs/iomap/direct-io.c:665
 ext4_dio_write_iter fs/ext4/file.c:609 [inline]
 ext4_file_write_iter+0x1102/0x1880 fs/ext4/file.c:720
 call_write_iter include/linux/fs.h:1871 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x981/0xda0 fs/read_write.c:584
 ksys_write+0x122/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f4828f26cd9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4820ae9208 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000034 RCX: 00007f4828f26cd9
RDX: 0000000000000012 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f4828fa4790 R08: 00007f4828fa4798 R09: 00007f4828fa4798
R10: 00007f4828fa4798 R11: 0000000000000246 R12: 00007f4828fa479c
R13: 00007ffef851f96f R14: 00007f4820ae9300 R15: 0000000000022000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_ext_mark_unwritten fs/ext4/ext4_extents.h:200 [inline]
RIP: 0010:ext4_split_extent_at+0xd11/0xe10 fs/ext4/extents.c:3221
Code: e9 d2 f8 ff ff e8 1f 6d 5d ff 66 81 c5 00 80 e9 32 fd ff ff e8 10 6d 5d ff 44 8d bd 00 80 ff ff e9 d1 fc ff ff e8 ff 6c 5d ff <0f> 0b 48 8b 7c 24 18 e8 73 9d b0 ff e9 7f f3 ff ff 48 89 cf e8 46
RSP: 0018:ffffc900055ef268 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88807d9c0000 RSI: ffffffff82277271 RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88807587d00c
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88807587d012
FS:  00007f4820ae9700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffef85799a0 CR3: 0000000028105000 CR4: 0000000000350ee0

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/08 23:45 upstream 8689f4f2ea56 668cb1fa .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-root kernel BUG in ext4_split_extent_at
2023/11/02 00:14 upstream 8bc9e6515183 69904c9f .config console log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-smack-root kernel BUG in ext4_split_extent_at
2023/06/09 05:46 upstream 25041a4c02c7 058b3a5a .config console log report syz [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs kernel BUG in ext4_split_extent_at
* Struck through repros no longer work on HEAD.