[syzbot] [gfs2?] general protection fault in gfs2_print_dbg (3)

syzbot
2025-09-15T18:18:29Z

Hello,

syzbot found the following issue on:

HEAD commit: 590b221ed425 Add linux-next specific files for 20250912
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=143eb642580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12a1d1f3a8199632
dashboard link: https://syzkaller.appspot.com/bug?extid=fa7122891ab9e0bbc6a7
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=111f9b62580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17888b62580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63a963fc26db/disk-590b221e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0c2013d30830/vmlinux-590b221e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ee4d3a8e8f6/bzImage-590b221e.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/37ba65492173/mount_4.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=14a23934580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fa7122891ab9e0bbc6a7@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xe7697c1115925d6c: 0000 [#1] SMP KASAN PTI
KASAN: maybe wild-memory-access in range [0x3b4c0088ac92eb60-0x3b4c0088ac92eb67]
CPU: 1 UID: 0 PID: 6163 Comm: syz.0.38 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:string_nocheck lib/vsprintf.c:653 [inline]
RIP: 0010:string+0x1bb/0x2b0 lib/vsprintf.c:735
Code: 15 a5 f6 eb b3 41 c1 fd 10 4c 89 6c 24 10 49 8d 5d ff 45 31 ed 4b 8d 3c 2c 48 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 75 60 4b 8d 2c 2e 47 0f b6 3c 2c 31 ff 44 89 fe
RSP: 0018:ffffc9000383ef00 EFLAGS: 00010007
RAX: 0769801115925d6c RBX: 00000000fffffffe RCX: dffffc0000000000
RDX: ffff88802a435ac0 RSI: 00000000ffff0a00 RDI: 3b4c0088ac92eb67
RBP: ffffffff8bf0acfe R08: ffff88802a435ac0 R09: 0000000000000008
R10: 0000000000000007 R11: 0000000000000000 R12: 3b4c0088ac92eb67
R13: 0000000000000000 R14: ffffc9000383f319 R15: 0000000000000030
FS: 00007fde6f5cd6c0(0000) GS:ffff888125ae8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f425685d000 CR3: 000000007d39e000 CR4: 00000000003526f0
Call Trace:
<TASK>
vsnprintf+0x739/0xf00 lib/vsprintf.c:2926
va_format lib/vsprintf.c:1728 [inline]
pointer+0x940/0x1190 lib/vsprintf.c:2548
vsnprintf+0x60f/0xf00 lib/vsprintf.c:2930
vprintk_store+0x3c7/0xd00 kernel/printk/printk.c:2252
vprintk_emit+0x15f/0x590 kernel/printk/printk.c:2399
_printk+0xcf/0x120 kernel/printk/printk.c:2448
gfs2_print_dbg+0x19a/0x1b0 fs/gfs2/glock.c:1444
dump_holder fs/gfs2/glock.c:2287 [inline]
gfs2_dump_glock+0x152d/0x1bc0 fs/gfs2/glock.c:2398
gfs2_consist_inode_i+0xf5/0x110 fs/gfs2/util.c:446
gfs2_dirent_scan+0x545/0x690 fs/gfs2/dir.c:-1
gfs2_dir_read+0x804/0x16f0 fs/gfs2/dir.c:1600
gfs2_readdir+0x14c/0x1b0 fs/gfs2/file.c:116
iterate_dir+0x399/0x570 fs/readdir.c:108
__do_sys_getdents64 fs/readdir.c:410 [inline]
__se_sys_getdents64+0xe4/0x260 fs/readdir.c:396
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fde6e78eba9
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:00007fde6f5cd038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fde6e9d6090 RCX: 00007fde6e78eba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007fde6e811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fde6e9d6128 R14: 00007fde6e9d6090 R15: 00007ffeeef80a98
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:string_nocheck lib/vsprintf.c:653 [inline]
RIP: 0010:string+0x1bb/0x2b0 lib/vsprintf.c:735
Code: 15 a5 f6 eb b3 41 c1 fd 10 4c 89 6c 24 10 49 8d 5d ff 45 31 ed 4b 8d 3c 2c 48 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 75 60 4b 8d 2c 2e 47 0f b6 3c 2c 31 ff 44 89 fe
RSP: 0018:ffffc9000383ef00 EFLAGS: 00010007
RAX: 0769801115925d6c RBX: 00000000fffffffe RCX: dffffc0000000000
RDX: ffff88802a435ac0 RSI: 00000000ffff0a00 RDI: 3b4c0088ac92eb67
RBP: ffffffff8bf0acfe R08: ffff88802a435ac0 R09: 0000000000000008
R10: 0000000000000007 R11: 0000000000000000 R12: 3b4c0088ac92eb67
R13: 0000000000000000 R14: ffffc9000383f319 R15: 0000000000000030
FS: 00007fde6f5cd6c0(0000) GS:ffff888125ae8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f425685d000 CR3: 000000007d39e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 15 a5 f6 eb b3 adc $0xb3ebf6a5,%eax
5: 41 c1 fd 10 sar $0x10,%r13d
9: 4c 89 6c 24 10 mov %r13,0x10(%rsp)
e: 49 8d 5d ff lea -0x1(%r13),%rbx
12: 45 31 ed xor %r13d,%r13d
15: 4b 8d 3c 2c lea (%r12,%r13,1),%rdi
19: 48 89 f8 mov %rdi,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 75 60 jne 0x92
32: 4b 8d 2c 2e lea (%r14,%r13,1),%rbp
36: 47 0f b6 3c 2c movzbl (%r12,%r13,1),%r15d
3b: 31 ff xor %edi,%edi
3d: 44 89 fe mov %r15d,%esi

---
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