Date:   Mon, 4 Sep 2023 16:11:45 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     syzbot <syzbot+4a08ffdf3667b36650a1@...kaller.appspotmail.com>,
        adilger.kernel@...ger.ca, djwong@...nel.org,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
        song@...nel.org, syzkaller-bugs@...glegroups.com, tytso@....edu,
        zhang_shurong@...mail.com
Cc:     "yukuai (C)" <yukuai3@...wei.com>,
        "yangerkun@...wei.com" <yangerkun@...wei.com>
Subject: Re: [syzbot] [xfs?] [ext4?] kernel BUG in __block_write_begin_int

Hi,

在 2023/09/04 15:29, syzbot 写道:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0468be89b3fa Merge tag 'iommu-updates-v6.6' of git://git.k..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=11145910680000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3d78b3780d210e21
> dashboard link: https://syzkaller.appspot.com/bug?extid=4a08ffdf3667b36650a1
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=164f7a57a80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=143b0298680000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f3914b539822/disk-0468be89.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6128b0644784/vmlinux-0468be89.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/349d98668c3a/bzImage-0468be89.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/75bd68910fd4/mount_0.gz
> 
> The issue was bisected to:
> 
> commit 8b0472b50bcf0f19a5119b00a53b63579c8e1e4d
> Author: Zhang Shurong <zhang_shurong@...mail.com>
> Date:   Sat Jul 22 07:53:53 2023 +0000
> 
>      md: raid1: fix potential OOB in raid1_remove_disk()
> 

Really? raid1 is not even used from the c reproducer, this bisect result
is insane.

Thanks,
Kuai

> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16e52577a80000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=15e52577a80000
> console output: https://syzkaller.appspot.com/x/log.txt?x=11e52577a80000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+4a08ffdf3667b36650a1@...kaller.appspotmail.com
> Fixes: 8b0472b50bcf ("md: raid1: fix potential OOB in raid1_remove_disk()")
> 
> ------------[ cut here ]------------
> kernel BUG at fs/buffer.c:2028!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 5187 Comm: syz-executor424 Not tainted 6.5.0-syzkaller-10885-g0468be89b3fa #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
> RIP: 0010:iomap_to_bh fs/buffer.c:2028 [inline]
> RIP: 0010:__block_write_begin_int+0x18f7/0x1a40 fs/buffer.c:2111
> Code: af 0d 85 ff 48 8b 7c 24 08 48 c7 c6 20 22 18 8b e8 6e 8b c6 ff 0f 0b e8 97 0d 85 ff eb 13 e8 90 0d 85 ff eb c7 e8 89 0d 85 ff <0f> 0b e8 82 0d 85 ff 48 8b 7c 24 08 48 c7 c6 20 22 18 8b e8 41 8b
> RSP: 0018:ffffc9000418f520 EFLAGS: 00010293
> RAX: ffffffff82087b37 RBX: 0000000000040000 RCX: ffff888078093b80
> RDX: 0000000000000000 RSI: 0000000000040000 RDI: 00000000000d0000
> RBP: ffffc9000418f6b0 R08: ffffffff82086ba2 R09: 1ffff1100f27203a
> R10: dffffc0000000000 R11: ffffed100f27203b R12: 00000000000d0000
> R13: 0000000000000400 R14: 0000000000000000 R15: ffff8880793901d0
> FS:  00007f0623ec56c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020040000 CR3: 0000000067478000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   <TASK>
>   iomap_write_begin+0xaf6/0x1f00 fs/iomap/buffered-io.c:772
>   iomap_write_iter fs/iomap/buffered-io.c:907 [inline]
>   iomap_file_buffered_write+0x587/0x1020 fs/iomap/buffered-io.c:968
>   blkdev_buffered_write block/fops.c:634 [inline]
>   blkdev_write_iter+0x41d/0x5c0 block/fops.c:688
>   call_write_iter include/linux/fs.h:1985 [inline]
>   new_sync_write fs/read_write.c:491 [inline]
>   vfs_write+0x782/0xaf0 fs/read_write.c:584
>   ksys_write+0x1a0/0x2c0 fs/read_write.c:637
>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>   do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f0623f2b6c9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 71 19 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007f0623ec5218 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f0623fb9478 RCX: 00007f0623f2b6c9
> RDX: 000000000208e24b RSI: 0000000020000100 RDI: 0000000000000003
> RBP: 00007f0623fb9470 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0623f7f694
> R13: 00007f0623f7f1c0 R14: 0031656c69662f2e R15: 6f6f6c2f7665642f
>   </TASK>
> Modules linked in:
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:iomap_to_bh fs/buffer.c:2028 [inline]
> RIP: 0010:__block_write_begin_int+0x18f7/0x1a40 fs/buffer.c:2111
> Code: af 0d 85 ff 48 8b 7c 24 08 48 c7 c6 20 22 18 8b e8 6e 8b c6 ff 0f 0b e8 97 0d 85 ff eb 13 e8 90 0d 85 ff eb c7 e8 89 0d 85 ff <0f> 0b e8 82 0d 85 ff 48 8b 7c 24 08 48 c7 c6 20 22 18 8b e8 41 8b
> RSP: 0018:ffffc9000418f520 EFLAGS: 00010293
> RAX: ffffffff82087b37 RBX: 0000000000040000 RCX: ffff888078093b80
> RDX: 0000000000000000 RSI: 0000000000040000 RDI: 00000000000d0000
> RBP: ffffc9000418f6b0 R08: ffffffff82086ba2 R09: 1ffff1100f27203a
> R10: dffffc0000000000 R11: ffffed100f27203b R12: 00000000000d0000
> R13: 0000000000000400 R14: 0000000000000000 R15: ffff8880793901d0
> FS:  00007f0623ec56c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f0623f66850 CR3: 0000000067478000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> If the bug is already fixed, let syzbot know by replying with:
> #syz fix: exact-commit-title
> 
> 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.
> 
> If you want to overwrite bug's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the bug is a duplicate of another bug, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 
> .
> 

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