Re: [f2fs-dev] [PATCH 3/5] f2fs: sanity check on sit entry

[Chao Yu <chao@kernel.org>]

On 2018/4/25 13:46, Jaegeuk Kim wrote:
> syzbot hit the following crash on upstream commit
> 87ef12027b9b1dd0e0b12cf311fbcb19f9d92539 (Wed Apr 18 19:48:17 2018 +0000)
> Merge tag 'ceph-for-4.17-rc2' of git://github.com/ceph/ceph-client
> syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=83699adeb2d13579c31e
> 
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=5805208181407744
> syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=6005073343676416
> Raw console output: https://syzkaller.appspot.com/x/log.txt?id=6555047731134464
> Kernel config: https://syzkaller.appspot.com/x/.config?id=1808800213120130118
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+83699adeb2d13579c31e@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for details.
> If you forward the report, please keep this part and the footer.
> 
> F2FS-fs (loop0): Magic Mismatch, valid(0xf2f52010) - read(0x0)
> F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
> F2FS-fs (loop0): invalid crc value
> BUG: unable to handle kernel paging request at ffffed006b2a50c0
> PGD 21ffee067 P4D 21ffee067 PUD 21fbeb067 PMD 0
> Oops: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 4514 Comm: syzkaller989480 Not tainted 4.17.0-rc1+ #8
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:build_sit_entries fs/f2fs/segment.c:3653 [inline]
> RIP: 0010:build_segment_manager+0x7ef7/0xbf70 fs/f2fs/segment.c:3852
> RSP: 0018:ffff8801b102e5b0 EFLAGS: 00010a06
> RAX: 1ffff1006b2a50c0 RBX: 0000000000000004 RCX: 0000000000000001
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801ac74243e
> RBP: ffff8801b102f410 R08: ffff8801acbd46c0 R09: fffffbfff14d9af8
> R10: fffffbfff14d9af8 R11: ffff8801acbd46c0 R12: ffff8801ac742a80
> R13: ffff8801d9519100 R14: dffffc0000000000 R15: ffff880359528600
> FS:  0000000001e04880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffed006b2a50c0 CR3: 00000001ac6ac000 CR4: 00000000001406f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  f2fs_fill_super+0x4095/0x7bf0 fs/f2fs/super.c:2803
>  mount_bdev+0x30c/0x3e0 fs/super.c:1165
>  f2fs_mount+0x34/0x40 fs/f2fs/super.c:3020
>  mount_fs+0xae/0x328 fs/super.c:1268
>  vfs_kern_mount.part.34+0xd4/0x4d0 fs/namespace.c:1037
>  vfs_kern_mount fs/namespace.c:1027 [inline]
>  do_new_mount fs/namespace.c:2517 [inline]
>  do_mount+0x564/0x3070 fs/namespace.c:2847
>  ksys_mount+0x12d/0x140 fs/namespace.c:3063
>  __do_sys_mount fs/namespace.c:3077 [inline]
>  __se_sys_mount fs/namespace.c:3074 [inline]
>  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3074
>  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x443d6a
> RSP: 002b:00007ffd312813c8 EFLAGS: 00000297 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0000000020000c00 RCX: 0000000000443d6a
> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffd312813d0
> RBP: 0000000000000003 R08: 0000000020016a00 R09: 000000000000000a
> R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000004
> R13: 0000000000402c60 R14: 0000000000000000 R15: 0000000000000000
> RIP: build_sit_entries fs/f2fs/segment.c:3653 [inline] RSP: ffff8801b102e5b0
> RIP: build_segment_manager+0x7ef7/0xbf70 fs/f2fs/segment.c:3852 RSP: ffff8801b102e5b0
> CR2: ffffed006b2a50c0
> ---[ end trace a2034989e196ff17 ]---
> 
> Reported-and-tested-by: syzbot+83699adeb2d13579c31e@syzkaller.appspotmail.com
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,