linux-kernel - [syzbot] [ext4?] kernel BUG in ext4_mb_normalize

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Message-ID: <68194f73.050a0220.a19a9.0005.GAE@google.com>
Date: Mon, 05 May 2025 16:53:23 -0700
From: syzbot <syzbot+7fc5cde5fbe19897a469@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tytso@....edu
Subject: [syzbot] [ext4?] kernel BUG in ext4_mb_normalize_request

Hello,

syzbot found the following issue on:

HEAD commit:    4f79eaa2ceac kbuild: Properly disable -Wunterminated-strin..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148b3774580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a42a9d552788177b
dashboard link: https://syzkaller.appspot.com/bug?extid=7fc5cde5fbe19897a469
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/edbf5e3df590/disk-4f79eaa2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e9ed2fe174f6/vmlinux-4f79eaa2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c11b2a37db5c/bzImage-4f79eaa2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7fc5cde5fbe19897a469@...kaller.appspotmail.com

EXT4-fs: Ignoring removed nobh option
EXT4-fs: Ignoring removed bh option
EXT4-fs (loop9): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
EXT4-fs (loop9): start 0, size 131072, fe_logical 131136
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:4555!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 8509 Comm: syz.9.234 Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
RIP: 0010:ext4_mb_normalize_request+0x1cc9/0x1d00 fs/ext4/mballoc.c:4555
Code: f5 ac ff 48 8b 44 24 38 48 8b 38 48 c7 c6 80 37 7e 8b 48 c7 c2 80 4d 7e 8b 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 38 a5 09 00 90 <0f> 0b e8 60 26 4d ff 90 0f 0b e8 58 26 4d ff 90 0f 0b e8 50 26 4d
RSP: 0018:ffffc9000496ed40 EFLAGS: 00010246
RAX: a8a732223c46f100 RBX: 0000000000020040 RCX: a8a732223c46f100
RDX: ffffc9000dd70000 RSI: 0000000000023bd3 RDI: 0000000000023bd4
RBP: 0000000000000000 R08: ffffc9000496e8e7 R09: 1ffff9200092dd1c
R10: dffffc0000000000 R11: fffff5200092dd1d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS:  00007fec5d95a6c0(0000) GS:ffff888126200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9695f6e270 CR3: 00000000207e0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_mb_new_blocks+0xc59/0x46a0 fs/ext4/mballoc.c:6208
 ext4_ext_map_blocks+0x1618/0x67c0 fs/ext4/extents.c:4379
 ext4_map_create_blocks fs/ext4/inode.c:520 [inline]
 ext4_map_blocks+0x807/0x1740 fs/ext4/inode.c:706
 _ext4_get_block+0x200/0x4c0 fs/ext4/inode.c:785
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:818
 ext4_block_write_begin+0x543/0x1290 fs/ext4/inode.c:1067
 ext4_write_begin+0x6f6/0x12c0 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x33a/0xa60 fs/ext4/inode.c:2932
 generic_perform_write+0x2c4/0x910 mm/filemap.c:4103
 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:591 [inline]
 vfs_write+0x548/0xa90 fs/read_write.c:684
 ksys_pwrite64 fs/read_write.c:791 [inline]
 __do_sys_pwrite64 fs/read_write.c:799 [inline]
 __se_sys_pwrite64 fs/read_write.c:796 [inline]
 __x64_sys_pwrite64+0x193/0x220 fs/read_write.c:796
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fec5cb8e969
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:00007fec5d95a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fec5cdb6080 RCX: 00007fec5cb8e969
RDX: 00000000000155c2 RSI: 0000200000000140 RDI: 000000000000000a
RBP: 00007fec5cc10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c64 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fec5cdb6080 R15: 00007fffed56a588
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_mb_normalize_request+0x1cc9/0x1d00 fs/ext4/mballoc.c:4555
Code: f5 ac ff 48 8b 44 24 38 48 8b 38 48 c7 c6 80 37 7e 8b 48 c7 c2 80 4d 7e 8b 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 38 a5 09 00 90 <0f> 0b e8 60 26 4d ff 90 0f 0b e8 58 26 4d ff 90 0f 0b e8 50 26 4d
RSP: 0018:ffffc9000496ed40 EFLAGS: 00010246
RAX: a8a732223c46f100 RBX: 0000000000020040 RCX: a8a732223c46f100
RDX: ffffc9000dd70000 RSI: 0000000000023bd3 RDI: 0000000000023bd4
RBP: 0000000000000000 R08: ffffc9000496e8e7 R09: 1ffff9200092dd1c
R10: dffffc0000000000 R11: fffff5200092dd1d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS:  00007fec5d95a6c0(0000) GS:ffff888126200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562fcaf64131 CR3: 00000000207e0000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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