syzbot


general protection fault in detach_extent_buffer_folio (3)

Status: moderation: reported on 2026/04/12 11:37
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+513d3e89d6cd9be3c461@syzkaller.appspotmail.com
First crash: 7d15h, last: 2d21h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in detach_extent_buffer_folio (2) btrfs 2 1 125d 121d 0/29 auto-obsoleted due to no activity on 2026/03/21 10:36
upstream general protection fault in detach_extent_buffer_folio btrfs 2 9 663d 679d 26/29 fixed on 2024/07/09 19:14

Sample crash report:
loop0: detected capacity change from 0 to 32768
btrfs: Deprecated parameter 'usebackuproot'
BTRFS warning: 'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead
BTRFS: device fsid c9fe44da-de57-406a-8241-57ec7d4412cf devid 1 transid 8 /dev/loop0 (7:0) scanned by syz.0.0 (5322)
BTRFS info (device loop0): first mount of filesystem c9fe44da-de57-406a-8241-57ec7d4412cf
BTRFS info (device loop0): using crc32c checksum algorithm
BTRFS info (device loop0): rebuilding free space tree
BTRFS info (device loop0): enabling ssd optimizations
BTRFS info (device loop0): using spread ssd allocation scheme
BTRFS info (device loop0): disabling tree log
BTRFS info (device loop0): enabling free space tree
BTRFS info (device loop0): force clearing of disk cache
BTRFS info (device loop0): trying to use backup root at mount time
BTRFS info (device loop0): force zlib compression, level 3
Oops: general protection fault, probably for non-canonical address 0xdffffc000000002a: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000150-0x0000000000000157]
CPU: 0 UID: 0 PID: 5322 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 e9 c0 19 83 09 cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc9000e34e488 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffffffff8bb47e1e RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8bb47e1e RDI: 000000000000002a
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1003e0b3a7 R12: 0000000000000000
R13: 0000000000000150 R14: 0000000000000150 R15: 0000000000000001
FS:  00007f4cdf5286c0(0000) GS:ffff88808ca49000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f76b1b05190 CR3: 0000000043d60000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 __kasan_check_byte+0x12/0x40 mm/kasan/common.c:573
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x79/0x2e0 kernel/locking/lockdep.c:5842
 __raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:341 [inline]
 detach_extent_buffer_folio+0xda/0x910 fs/btrfs/extent_io.c:2940
 btrfs_release_extent_buffer_folios+0x68/0x440 fs/btrfs/extent_io.c:3000
 release_extent_buffer+0x16b/0x240 fs/btrfs/extent_io.c:3649
 btrfs_force_cow_block+0x138c/0x2510 fs/btrfs/ctree.c:591
 btrfs_cow_block+0x3c4/0xa90 fs/btrfs/ctree.c:694
 btrfs_search_slot+0xd20/0x2d20 fs/btrfs/ctree.c:2116
 lookup_inline_extent_backref+0x36f/0x1a70 fs/btrfs/extent-tree.c:848
 lookup_extent_backref fs/btrfs/extent-tree.c:1100 [inline]
 __btrfs_free_extent+0x456/0x4570 fs/btrfs/extent-tree.c:3319
 run_delayed_tree_ref fs/btrfs/extent-tree.c:1824 [inline]
 run_one_delayed_ref fs/btrfs/extent-tree.c:1851 [inline]
 btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:2058 [inline]
 __btrfs_run_delayed_refs+0x1881/0x4780 fs/btrfs/extent-tree.c:2133
 btrfs_run_delayed_refs+0xe6/0x3b0 fs/btrfs/extent-tree.c:2245
 btrfs_commit_transaction+0x29a/0x31a0 fs/btrfs/transaction.c:2254
 btrfs_sync_file+0xdee/0x1260 fs/btrfs/file.c:1817
 generic_write_sync include/linux/fs.h:2640 [inline]
 btrfs_do_write_iter+0x72e/0x880 fs/btrfs/file.c:1468
 iter_file_splice_write+0x9a1/0x10f0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1159
 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1228
 do_sendfile+0x535/0x7d0 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4cde59c819
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:00007f4cdf527fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f4cde815fa0 RCX: 00007f4cde59c819
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f4cde632c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000fffe82 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4cde816038 R14: 00007f4cde815fa0 R15: 00007ffe1a120088
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 e9 c0 19 83 09 cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc9000e34e488 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffffffff8bb47e1e RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8bb47e1e RDI: 000000000000002a
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1003e0b3a7 R12: 0000000000000000
R13: 0000000000000150 R14: 0000000000000150 R15: 0000000000000001
FS:  00007f4cdf5286c0(0000) GS:ffff88808ca49000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f76b1b05190 CR3: 0000000043d60000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess), 4 bytes skipped:
   0:	0f 1f 40 00          	nopl   0x0(%rax)
   4:	90                   	nop
   5:	90                   	nop
   6:	90                   	nop
   7:	90                   	nop
   8:	90                   	nop
   9:	90                   	nop
   a:	90                   	nop
   b:	90                   	nop
   c:	90                   	nop
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	0f 1f 40 d6          	nopl   -0x2a(%rax)
  18:	48 c1 ef 03          	shr    $0x3,%rdi
  1c:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  23:	fc ff df
* 26:	0f b6 04 07          	movzbl (%rdi,%rax,1),%eax <-- trapping instruction
  2a:	3c 08                	cmp    $0x8,%al
  2c:	0f 92 c0             	setb   %al
  2f:	e9 c0 19 83 09       	jmp    0x98319f4
  34:	cc                   	int3
  35:	66                   	data16
  36:	66                   	data16
  37:	66                   	data16
  38:	66                   	data16
  39:	66                   	data16
  3a:	66                   	data16
  3b:	2e                   	cs

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/13 05:09 upstream 028ef9c96e96 38c8e246 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in detach_extent_buffer_folio
2026/04/08 11:28 upstream 3036cd0d3328 2c961e87 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in detach_extent_buffer_folio
* Struck through repros no longer work on HEAD.