From: syzbot <syzbot+41453ea05ab61c075f1f@syzkaller.appspotmail.com>
To: jack@suse.com, linux-ext4@vger.kernel.org,
linux-kernel@vger.kernel.org, pavankumaryalagada@gmail.com,
syzkaller-bugs@googlegroups.com, tytso@mit.edu
Subject: Re: [syzbot] [ext4?] general protection fault in __bh_submit
Date: Fri, 04 Sep 2026 05:04:27 -0700 [thread overview]
Message-ID: <6a9ab3cb.9266084e.bf0d7.0668.GAE@google.com> (raw)
In-Reply-To: <6a964b83.99c12218.408a8.0001.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: 9d80aa4617b3 Add linux-next specific files for 20260903
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15fa38f9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bb4a32c282cc2ec7
dashboard link: https://syzkaller.appspot.com/bug?extid=41453ea05ab61c075f1f
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17c228f9580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13fa38f9580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/417a63e8ac61/disk-9d80aa46.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a1d004c189c1/vmlinux-9d80aa46.xz
kernel image: https://storage.googleapis.com/syzbot-assets/97413e5bd243/bzImage-9d80aa46.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/21b9bcefd2ef/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=100508f9580000)
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41453ea05ab61c075f1f@syzkaller.appspotmail.com
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 UID: 0 PID: 4945 Comm: jbd2/sda1-8 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:const_folio_flags include/linux/page-flags.h:345 [inline]
RIP: 0010:folio_test_dropbehind include/linux/page-flags.h:600 [inline]
RIP: 0010:__bh_submit+0x22d/0x8d0 fs/buffer.c:1109
Code: c1 e8 03 48 89 44 24 18 42 80 3c 20 00 74 08 48 89 df e8 f6 e7 d7 ff 48 89 5c 24 28 48 8b 1b 4c 8d 7b 08 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 d4 e7 d7 ff 4d 8b 3f 4c 89 fe 48
RSP: 0018:ffffc9000753f868 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff84b9a9a9
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff8880739467a0
RBP: 0000000000009801 R08: ffff8880739467ff R09: 1ffff1100e728cff
R10: dffffc0000000000 R11: ffffed100e728d00 R12: dffffc0000000000
R13: ffff888073946780 R14: ffff888076b240e0 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff888124cc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffa1d208708 CR3: 000000000eb48000 CR4: 00000000003526f0
Call Trace:
<TASK>
jbd2_journal_commit_transaction+0x2285/0x5c80 fs/jbd2/commit.c:751
kjournald2+0x3bc/0x740 fs/jbd2/journal.c:200
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 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:const_folio_flags include/linux/page-flags.h:345 [inline]
RIP: 0010:folio_test_dropbehind include/linux/page-flags.h:600 [inline]
RIP: 0010:__bh_submit+0x22d/0x8d0 fs/buffer.c:1109
Code: c1 e8 03 48 89 44 24 18 42 80 3c 20 00 74 08 48 89 df e8 f6 e7 d7 ff 48 89 5c 24 28 48 8b 1b 4c 8d 7b 08 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 d4 e7 d7 ff 4d 8b 3f 4c 89 fe 48
RSP: 0018:ffffc9000753f868 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff84b9a9a9
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff8880739467a0
RBP: 0000000000009801 R08: ffff8880739467ff R09: 1ffff1100e728cff
R10: dffffc0000000000 R11: ffffed100e728d00 R12: dffffc0000000000
R13: ffff888073946780 R14: ffff888076b240e0 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff888124cc0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffa1d208708 CR3: 000000007f076000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: c1 e8 03 shr $0x3,%eax
3: 48 89 44 24 18 mov %rax,0x18(%rsp)
8: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
d: 74 08 je 0x17
f: 48 89 df mov %rbx,%rdi
12: e8 f6 e7 d7 ff call 0xffd7e80d
17: 48 89 5c 24 28 mov %rbx,0x28(%rsp)
1c: 48 8b 1b mov (%rbx),%rbx
1f: 4c 8d 7b 08 lea 0x8(%rbx),%r15
23: 4c 89 f8 mov %r15,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 ff mov %r15,%rdi
34: e8 d4 e7 d7 ff call 0xffd7e80d
39: 4d 8b 3f mov (%r15),%r15
3c: 4c 89 fe mov %r15,%rsi
3f: 48 rex.W
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
prev parent reply other threads:[~2026-09-04 12:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-01 3:50 [syzbot] [ext4?] general protection fault in __bh_submit syzbot
2026-09-04 12:04 ` syzbot [this message]
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