LinuxLists.cc - [syzbot] kernel BUG in ext4_do

2022-12-17 20:26:18

Subject: [syzbot] kernel BUG in ext4_do_writepages

Hello,

syzbot found the following issue on:

HEAD commit: 02bf43c7b7f7 Merge tag 'fs.xattr.simple.rework.rbtree.rwlo..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16d48f33880000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c59170b68d26a55
dashboard link: https://syzkaller.appspot.com/bug?extid=d1da16f03614058fdc48
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=166cffdf880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=172b1f2b880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/45f211dceffb/disk-02bf43c7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fd0c63aa3713/vmlinux-02bf43c7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/734647e04fd0/bzImage-02bf43c7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/192035fab0d1/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2782!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 1100 Comm: kworker/u4:5 Not tainted 6.1.0-syzkaller-03295-g02bf43c7b7f7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: writeback wb_workfn (flush-7:1)
RIP: 0010:ext4_do_writepages+0x3c27/0x3c30 fs/ext4/inode.c:2781
Code: c7 50 d6 4b 8d 4c 89 fa e8 46 c9 33 02 e9 c0 fb ff ff e8 4c 7b 53 ff 0f 0b e8 45 7b 53 ff 0f 0b e8 fe 4d 5c 08 e8 39 7b 53 ff <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 53 48 89 fb 49 bf 00 00
RSP: 0018:ffffc90004ffede0 EFLAGS: 00010293
RAX: ffffffff8237eaa7 RBX: 0000008000000000 RCX: ffff8880207dd7c0
RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000
RBP: ffffc90004fff150 R08: ffffffff8237b469 R09: ffffed100e7b8791
R10: ffffed100e7b8791 R11: 1ffff1100e7b8790 R12: ffff888073dc3ee0
R13: ffffc90004fff650 R14: 0000008410000000 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f224f000000 CR3: 0000000019fee000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ext4_writepages+0x1e0/0x290 fs/ext4/inode.c:2965
do_writepages+0x3c3/0x680 mm/page-writeback.c:2469
__writeback_single_inode+0xd1/0x670 fs/fs-writeback.c:1587
writeback_sb_inodes+0xb3b/0x18f0 fs/fs-writeback.c:1878
__writeback_inodes_wb+0x125/0x420 fs/fs-writeback.c:1949
wb_writeback+0x440/0x7b0 fs/fs-writeback.c:2054
wb_check_background_flush fs/fs-writeback.c:2120 [inline]
wb_do_writeback fs/fs-writeback.c:2208 [inline]
wb_workfn+0xb3f/0xef0 fs/fs-writeback.c:2235
process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
kthread+0x266/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_do_writepages+0x3c27/0x3c30 fs/ext4/inode.c:2781
Code: c7 50 d6 4b 8d 4c 89 fa e8 46 c9 33 02 e9 c0 fb ff ff e8 4c 7b 53 ff 0f 0b e8 45 7b 53 ff 0f 0b e8 fe 4d 5c 08 e8 39 7b 53 ff <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 53 48 89 fb 49 bf 00 00
RSP: 0018:ffffc90004ffede0 EFLAGS: 00010293
RAX: ffffffff8237eaa7 RBX: 0000008000000000 RCX: ffff8880207dd7c0
RDX: 0000000000000000 RSI: 0000008000000000 RDI: 0000000000000000
RBP: ffffc90004fff150 R08: ffffffff8237b469 R09: ffffed100e7b8791
R10: ffffed100e7b8791 R11: 1ffff1100e7b8790 R12: ffff888073dc3ee0
R13: ffffc90004fff650 R14: 0000008410000000 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f224f0df000 CR3: 0000000021186000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

---
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2023-10-27 00:06:06

by syzbot

[permalink] [raw]

Subject: Re: [syzbot] kernel BUG in ext4_do_writepages

This bug is marked as fixed by commit:
ext4: fix race condition between buffer write and page_mkwrite

But I can't find it in the tested trees[1] for more than 90 days.
Is it a correct commit? Please update it by replying:

#syz fix: exact-commit-title

Until then the bug is still considered open and new crashes with
the same signature are ignored.

Kernel: Linux
Dashboard link: https://syzkaller.appspot.com/bug?extid=d1da16f03614058fdc48

---
[1] I expect the commit to be present in:

1. for-kernelci branch of
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

2. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git

3. master branch of
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git

4. main branch of
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git

The full list of 9 trees can be found at
https://syzkaller.appspot.com/upstream/repos