syzbot
kernel BUG in ext4_es_cache_extent
Status:
upstream: reported C repro on 2026/03/06 16:01
Bug presence:
origin:upstream
Labels:
missing-backport
[Documentation on labels]
Reported-by: syzbot+69319f3f3c680030db3e@syzkaller.appspotmail.com
First crash: 152d, last: 105d
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Last patch testing requests (2)
Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/extents_status.c:967!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 832 Comm: syz.1.112 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:ext4_es_cache_extent+0x57b/0x5d0 fs/ext4/extents_status.c:967
Code: e8 03 42 80 3c 38 00 74 08 48 89 df e8 de 27 cf ff 48 8b 3b 48 8b 74 24 28 48 8d 54 24 60 e8 3c fa 0c 00 eb 13 e8 45 f5 89 ff <0f> 0b e8 3e f5 89 ff eb 28 e8 37 f5 89 ff 31 f6 65 ff 0d f6 f5 1a
RSP: 0018:ffffc9000197e7a0 EFLAGS: 00010293
RAX: ffffffff81e777bb RBX: 000000000000009c RCX: ffff888119df2880
RDX: 0000000000000000 RSI: 000000000000009c RDI: 0000000000000097
RBP: ffffc9000197e8a8 R08: ffffc9000197e817 R09: ffffc9000197e800
R10: dffffc0000000000 R11: fffff5200032fd03 R12: ffff88810e1323c8
R13: 47ffffffffffffff R14: 0000000000000097 R15: dffffc0000000000
FS: 000055556c974500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555be5b888 CR3: 000000012d00a000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ext4_cache_extents fs/ext4/extents.c:536 [inline]
__read_extent_tree_block+0x44b/0x790 fs/ext4/extents.c:583
ext4_find_extent+0x8b9/0xe20 fs/ext4/extents.c:936
ext4_ext_map_blocks+0x207/0x61d0 fs/ext4/extents.c:4166
ext4_map_blocks+0x9d8/0x1b70 fs/ext4/inode.c:679
_ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:822
ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:855
ext4_block_write_begin+0x594/0x1280 fs/ext4/inode.c:1124
ext4_write_begin+0x600/0xf90 fs/ext4/ext4_jbd2.h:-1
ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3001
generic_perform_write+0x32d/0x740 mm/filemap.c:3903
ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285
ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1
do_iter_readv_writev fs/read_write.c:-1 [inline]
do_iter_write+0x665/0xb40 fs/read_write.c:861
vfs_iter_write+0x7d/0xa0 fs/read_write.c:902
iter_file_splice_write+0x69e/0xcd0 fs/splice.c:685
do_splice_from fs/splice.c:763 [inline]
direct_splice_actor+0xf7/0x130 fs/splice.c:930
splice_direct_to_actor+0x4ad/0xb30 fs/splice.c:885
do_splice_direct+0x1c2/0x2d0 fs/splice.c:973
do_sendfile+0x5ed/0xea0 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64 fs/read_write.c:1309 [inline]
__x64_sys_sendfile64+0x199/0x1f0 fs/read_write.c:1309
x64_sys_call+0x62c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f3ac599c799
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:00007fffa3e85588 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f3ac5c15fa0 RCX: 00007f3ac599c799
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 00007f3ac5a32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000003ffff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3ac5c15fac R14: 00007f3ac5c15fa0 R15: 00007f3ac5c15fa0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_es_cache_extent+0x57b/0x5d0 fs/ext4/extents_status.c:967
Code: e8 03 42 80 3c 38 00 74 08 48 89 df e8 de 27 cf ff 48 8b 3b 48 8b 74 24 28 48 8d 54 24 60 e8 3c fa 0c 00 eb 13 e8 45 f5 89 ff <0f> 0b e8 3e f5 89 ff eb 28 e8 37 f5 89 ff 31 f6 65 ff 0d f6 f5 1a
RSP: 0018:ffffc9000197e7a0 EFLAGS: 00010293
RAX: ffffffff81e777bb RBX: 000000000000009c RCX: ffff888119df2880
RDX: 0000000000000000 RSI: 000000000000009c RDI: 0000000000000097
RBP: ffffc9000197e8a8 R08: ffffc9000197e817 R09: ffffc9000197e800
R10: dffffc0000000000 R11: fffff5200032fd03 R12: ffff88810e1323c8
R13: 47ffffffffffffff R14: 0000000000000097 R15: dffffc0000000000
FS: 000055556c974500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6fb79a9000 CR3: 000000012d00a000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
* Struck through repros no longer work on HEAD.