syzbot


general protection fault in __hfsplus_brec_find

Status: moderation: reported on 2026/01/20 13:30
Subsystems: hfs
[Documentation on labels]
Reported-by: syzbot+63c5597a683630268757@syzkaller.appspotmail.com
First crash: 5d10h, last: 5d10h

Sample crash report:
loop0: detected capacity change from 0 to 1024
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 UID: 0 PID: 5337 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~bpo12+1 04/01/2014
RIP: 0010:__hfsplus_brec_find+0xad/0x480 fs/hfsplus/bfind.c:113
Code: 74 24 28 4d 85 f6 0f 84 db 03 00 00 66 c7 44 24 60 00 00 c7 84 24 80 00 00 00 00 00 00 00 4d 8d 74 24 18 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 d6 02 00 00 48 89 5c 24 30 41 0f b7 06
RSP: 0000:ffffc9000dba76e0 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 1ffff92001b74ee4 RCX: ffff888035fb24c0
RDX: 0000000000000000 RSI: ffffc9000dba79e0 RDI: fffffffffffffffb
RBP: ffffc9000dba77d0 R08: 0000030000000600 R09: 0000030000000600
R10: dffffc0000000000 R11: ffffed100822cc01 R12: fffffffffffffffb
R13: dffffc0000000000 R14: 0000000000000013 R15: ffffc9000dba79e0
FS:  00007fe9a62126c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffbfa97fc0 CR3: 0000000041be5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 hfsplus_brec_insert+0x8c6/0xd70 fs/hfsplus/brec.c:160
 hfsplus_create_cat+0x9a9/0x10d0 fs/hfsplus/catalog.c:308
 hfsplus_mknod+0x16a/0x290 fs/hfsplus/dir.c:494
 vfs_create+0x3aa/0x400 fs/namei.c:4132
 do_mknodat+0x3ea/0x610 fs/namei.c:5039
 __do_sys_mknod fs/namei.c:5076 [inline]
 __se_sys_mknod fs/namei.c:5074 [inline]
 __x64_sys_mknod+0x8c/0xa0 fs/namei.c:5074
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9a538f7c9
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:00007fe9a6212038 EFLAGS: 00000246 ORIG_RAX: 0000000000000085
RAX: ffffffffffffffda RBX: 00007fe9a55e5fa0 RCX: 00007fe9a538f7c9
RDX: 0000000000000701 RSI: 0000000000000000 RDI: 0000200000000000
RBP: 00007fe9a5413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe9a55e6038 R14: 00007fe9a55e5fa0 R15: 00007fffbfa98798
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hfsplus_brec_find+0xad/0x480 fs/hfsplus/bfind.c:113
Code: 74 24 28 4d 85 f6 0f 84 db 03 00 00 66 c7 44 24 60 00 00 c7 84 24 80 00 00 00 00 00 00 00 4d 8d 74 24 18 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 d6 02 00 00 48 89 5c 24 30 41 0f b7 06
RSP: 0000:ffffc9000dba76e0 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 1ffff92001b74ee4 RCX: ffff888035fb24c0
RDX: 0000000000000000 RSI: ffffc9000dba79e0 RDI: fffffffffffffffb
RBP: ffffc9000dba77d0 R08: 0000030000000600 R09: 0000030000000600
R10: dffffc0000000000 R11: ffffed100822cc01 R12: fffffffffffffffb
R13: dffffc0000000000 R14: 0000000000000013 R15: ffffc9000dba79e0
FS:  00007fe9a62126c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffbfa97fc0 CR3: 0000000041be5000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	74 24                	je     0x26
   2:	28 4d 85             	sub    %cl,-0x7b(%rbp)
   5:	f6 0f 84             	testb  $0x84,(%rdi)
   8:	db 03                	fildl  (%rbx)
   a:	00 00                	add    %al,(%rax)
   c:	66 c7 44 24 60 00 00 	movw   $0x0,0x60(%rsp)
  13:	c7 84 24 80 00 00 00 	movl   $0x0,0x80(%rsp)
  1a:	00 00 00 00
  1e:	4d 8d 74 24 18       	lea    0x18(%r12),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 d6 02 00 00    	jne    0x30d
  37:	48 89 5c 24 30       	mov    %rbx,0x30(%rsp)
  3c:	41 0f b7 06          	movzwl (%r14),%eax

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/16 13:27 upstream 54e82e93ca93 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in __hfsplus_brec_find
* Struck through repros no longer work on HEAD.