Re: [syzbot] [block?] general protection fault in bio_alloc_bioset
From: syzbot
Date: Sat Mar 21 2026 - 02:48:05 EST
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in bio_alloc_bioset
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 5172 Comm: jbd2/sda1-8 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:bio_init block/bio.c:214 [inline]
RIP: 0010:bio_init_inline include/linux/bio.h:435 [inline]
RIP: 0010:bio_alloc_bioset+0x67e/0xc30 block/bio.c:597
Code: 04 24 00 00 00 00 41 8d 46 ff 0f b7 d8 bf 04 00 00 00 89 de e8 33 6c 3c fd 66 83 fb 04 0f 83 db 00 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 c4 cf a5 fd 49 c7 07 00 00 00 00 49
RSP: 0018:ffffc9000e6ef7e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88803778bd00 RSI: 0000000000000000 RDI: 0000000000000004
RBP: dffffc0000000000 R08: ffffffff903445f7 R09: 1ffffffff20688be
R10: dffffc0000000000 R11: fffffbfff20688bf R12: 0000000000092800
R13: ffffffff9a6ca840 R14: 0000000000000001 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124ff3000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f6b59c76f CR3: 000000007cd28000 CR4: 00000000003526f0
Call Trace:
<TASK>
bio_alloc include/linux/bio.h:373 [inline]
submit_bh_wbc+0x22d/0x650 fs/buffer.c:2816
jbd2_journal_commit_transaction+0x2186/0x5ad0 fs/jbd2/commit.c:726
kjournald2+0x3e0/0x760 fs/jbd2/journal.c:201
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bio_init block/bio.c:214 [inline]
RIP: 0010:bio_init_inline include/linux/bio.h:435 [inline]
RIP: 0010:bio_alloc_bioset+0x67e/0xc30 block/bio.c:597
Code: 04 24 00 00 00 00 41 8d 46 ff 0f b7 d8 bf 04 00 00 00 89 de e8 33 6c 3c fd 66 83 fb 04 0f 83 db 00 00 00 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 c4 cf a5 fd 49 c7 07 00 00 00 00 49
RSP: 0018:ffffc9000e6ef7e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88803778bd00 RSI: 0000000000000000 RDI: 0000000000000004
RBP: dffffc0000000000 R08: ffffffff903445f7 R09: 1ffffffff20688be
R10: dffffc0000000000 R11: fffffbfff20688bf R12: 0000000000092800
R13: ffffffff9a6ca840 R14: 0000000000000001 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124ff3000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f6b59c76f CR3: 000000007cd28000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 04 24 add $0x24,%al
2: 00 00 add %al,(%rax)
4: 00 00 add %al,(%rax)
6: 41 8d 46 ff lea -0x1(%r14),%eax
a: 0f b7 d8 movzwl %ax,%ebx
d: bf 04 00 00 00 mov $0x4,%edi
12: 89 de mov %ebx,%esi
14: e8 33 6c 3c fd call 0xfd3c6c4c
19: 66 83 fb 04 cmp $0x4,%bx
1d: 0f 83 db 00 00 00 jae 0xfe
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ff mov %r15,%rdi
33: e8 c4 cf a5 fd call 0xfda5cffc
38: 49 c7 07 00 00 00 00 movq $0x0,(%r15)
3f: 49 rex.WB
Tested on:
commit: 785f0eb2 Add linux-next specific files for 20260320
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1646d0ca580000
kernel config: https://syzkaller.appspot.com/x/.config?x=22bf3527036b9be1
dashboard link: https://syzkaller.appspot.com/bug?extid=09ddb593eea76a158f42
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=1177a2f6580000