[Android 5.10] kernel BUG in ext4_ext_insert_extent

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dad37bbb13a8 Merge 5.10.251 into android13-5.10-lts
git tree: android13-5.10-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=12a997e6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef167f989dba92e
dashboard link: https://syzkaller.appspot.com/bug?extid=e67f274f1d95b6782e59
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13a04a02580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15de1552580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9d3036bfa4ed/disk-dad37bbb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c5a0794fe3b/vmlinux-dad37bbb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5422ae394213/bzImage-dad37bbb.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/0d48208cc8cb/mount_1.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=150f7b5a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e67f27...@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:2135!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 556 Comm: syz.4.38 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:ext4_ext_insert_extent+0x4592/0x45d0 fs/ext4/extents.c:2135
Code: ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c 08 e9 ff ff 48 89 df e8 6f 51 d4 ff e9 fb e8 ff ff e8 95 d0 99 ff 0f 0b e8 8e d0 99 ff <0f> 0b e8 87 d0 99 ff 0f 0b 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 30
RSP: 0018:ffffc90002026340 EFLAGS: 00010293
RAX: ffffffff81cae5c2 RBX: ffff8881316e4400 RCX: ffff88811a6ce2c0
RDX: 0000000000000000 RSI: 000000000000002d RDI: 000000000000002d
RBP: ffffc900020264f0 R08: ffff888131cf4157 R09: 1ffff1102639e82a
R10: dffffc0000000000 R11: ffffed102639e82b R12: 000000000000002d
R13: 1ffff11023607a68 R14: ffff8881316e4454 R15: 000000000000002d
FS: 00007f079736b6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000440bf CR3: 0000000114151000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
ext4_split_extent_at+0x79b/0xe90 fs/ext4/extents.c:3230
ext4_split_extent+0x1ba/0x4c0 fs/ext4/extents.c:3349
ext4_split_convert_extents fs/ext4/extents.c:3709 [inline]
ext4_ext_handle_unwritten_extents fs/ext4/extents.c:3870 [inline]
ext4_ext_map_blocks+0x1084/0x5dd0 fs/ext4/extents.c:4225
ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674
_ext4_get_block+0x1d1/0x4e0 fs/ext4/inode.c:817
ext4_get_block_unwritten+0x2a/0x40 fs/ext4/inode.c:848
ext4_block_write_begin+0x573/0x1340 fs/ext4/inode.c:1101
ext4_write_begin+0x67e/0x1690 fs/ext4/ext4_jbd2.h:-1
ext4_da_write_begin+0x478/0xf10 fs/ext4/inode.c:3033
generic_perform_write+0x2ce/0x540 mm/filemap.c:3509
ext4_buffered_write_iter+0x4b8/0x640 fs/ext4/file.c:271
ext4_file_write_iter+0x53f/0x1980 fs/ext4/file.c:-1
do_iter_readv_writev+0x478/0x5f0 fs/read_write.c:-1
do_iter_write+0x189/0x630 fs/read_write.c:866
vfs_iter_write+0x7d/0xa0 fs/read_write.c:907
iter_file_splice_write+0x68c/0xcb0 fs/splice.c:689
do_splice_from fs/splice.c:767 [inline]
direct_splice_actor+0xe9/0x120 fs/splice.c:936
splice_direct_to_actor+0x4cb/0xb30 fs/splice.c:891
do_splice_direct+0x1c2/0x2d0 fs/splice.c:979
do_sendfile+0x8df/0x1040 fs/read_write.c:1257
__do_sys_sendfile64 fs/read_write.c:1318 [inline]
__se_sys_sendfile64 fs/read_write.c:1304 [inline]
__x64_sys_sendfile64+0x199/0x1f0 fs/read_write.c:1304
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f0797529799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f079736b028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f07977a3090 RCX: 00007f0797529799
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007f07975bfbd9 R08: 0000000000000000 R09: 0000000000000000
R10: 000000007ffff000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f07977a3128 R14: 00007f07977a3090 R15: 00007ffc72026c08
Modules linked in:
---[ end trace d5d34d8361b49bf9 ]---
RIP: 0010:ext4_ext_insert_extent+0x4592/0x45d0 fs/ext4/extents.c:2135
Code: ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c 08 e9 ff ff 48 89 df e8 6f 51 d4 ff e9 fb e8 ff ff e8 95 d0 99 ff 0f 0b e8 8e d0 99 ff <0f> 0b e8 87 d0 99 ff 0f 0b 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 30
RSP: 0018:ffffc90002026340 EFLAGS: 00010293
RAX: ffffffff81cae5c2 RBX: ffff8881316e4400 RCX: ffff88811a6ce2c0
RDX: 0000000000000000 RSI: 000000000000002d RDI: 000000000000002d
RBP: ffffc900020264f0 R08: ffff888131cf4157 R09: 1ffff1102639e82a
R10: dffffc0000000000 R11: ffffed102639e82b R12: 000000000000002d
R13: 1ffff11023607a68 R14: ffff8881316e4454 R15: 000000000000002d
FS: 00007f079736b6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000440bf CR3: 0000000114151000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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