syzbot


kernel BUG in ext4_mb_normalize_request

Status: upstream: reported on 2025/05/05 23:53
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+7fc5cde5fbe19897a469@syzkaller.appspotmail.com
First crash: 101d, last: 20d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] kernel BUG in ext4_mb_normalize_request 0 (1) 2025/05/05 23:53

Sample crash report:
EXT4-fs (loop5): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
EXT4-fs (loop5): start 0, size 131072, fe_logical 131120
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:4555!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6476 Comm: syz.5.24 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:ext4_mb_normalize_request+0x1cc9/0x1d00 fs/ext4/mballoc.c:4555
Code: 49 ac ff 48 8b 44 24 38 48 8b 38 48 c7 c6 c0 75 9e 8b 48 c7 c2 c0 8b 9e 8b 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 98 a1 09 00 90 <0f> 0b e8 20 62 4c ff 90 0f 0b e8 18 62 4c ff 90 0f 0b e8 10 62 4c
RSP: 0018:ffffc9000529ed00 EFLAGS: 00010246
RAX: 557be792e57d1600 RBX: 0000000000020030 RCX: 557be792e57d1600
RDX: ffffc90004631000 RSI: 00000000000169e3 RDI: 00000000000169e4
RBP: 0000000000000000 R08: ffffc9000529e8e7 R09: 1ffff92000a53d1c
R10: dffffc0000000000 R11: fffff52000a53d1d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS:  00007f24676176c0(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fac9bbc4000 CR3: 000000002f7ba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 ext4_mb_new_blocks+0xc59/0x46a0 fs/ext4/mballoc.c:6208
 ext4_ext_map_blocks+0x161a/0x6ac0 fs/ext4/extents.c:4383
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x931/0x18d0 fs/ext4/inode.c:813
 _ext4_get_block+0x200/0x4c0 fs/ext4/inode.c:892
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:925
 ext4_block_write_begin+0x6f8/0x14b0 fs/ext4/inode.c:1178
 ext4_write_begin+0xa4f/0x1680 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x449/0xd20 fs/ext4/inode.c:3057
 generic_perform_write+0x2c7/0x910 mm/filemap.c:4112
 ext4_buffered_write_iter+0xce/0x3a0 fs/ext4/file.c:299
 ext4_file_write_iter+0x298/0x1bc0 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x548/0xa90 fs/read_write.c:686
 ksys_pwrite64 fs/read_write.c:793 [inline]
 __do_sys_pwrite64 fs/read_write.c:801 [inline]
 __se_sys_pwrite64 fs/read_write.c:798 [inline]
 __x64_sys_pwrite64+0x193/0x220 fs/read_write.c:798
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f246678e9a9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2467617038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f24669b5fa0 RCX: 00007f246678e9a9
RDX: 000000000000ff10 RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007f2466810d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f24669b5fa0 R15: 00007ffe2ede1c38
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_mb_normalize_request+0x1cc9/0x1d00 fs/ext4/mballoc.c:4555
Code: 49 ac ff 48 8b 44 24 38 48 8b 38 48 c7 c6 c0 75 9e 8b 48 c7 c2 c0 8b 9e 8b 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 98 a1 09 00 90 <0f> 0b e8 20 62 4c ff 90 0f 0b e8 18 62 4c ff 90 0f 0b e8 10 62 4c
RSP: 0018:ffffc9000529ed00 EFLAGS: 00010246
RAX: 557be792e57d1600 RBX: 0000000000020030 RCX: 557be792e57d1600
RDX: ffffc90004631000 RSI: 00000000000169e3 RDI: 00000000000169e4
RBP: 0000000000000000 R08: ffffc9000529e8e7 R09: 1ffff92000a53d1c
R10: dffffc0000000000 R11: fffff52000a53d1d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS:  00007f24676176c0(0000) GS:ffff888125c57000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055559e5a5290 CR3: 000000002f7ba000 CR4: 00000000003526f0

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/22 08:12 upstream 89be9a83ccf1 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in ext4_mb_normalize_request
2025/05/01 23:48 upstream 4f79eaa2ceac 51b137cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in ext4_mb_normalize_request
* Struck through repros no longer work on HEAD.