[PATCH v2] erofs: fix null-ptr-deref caused by erofs_xattr_prefixes_init

[Yue Hu]

On Mon, 15 May 2023 18:39:41 +0800
Jingbo Xu <jefflexu at linux.alibaba.com> wrote:

> Fragments and dedupe share one feature bit, and thus packed inode may not
> exist when fragment feature bit (dedupe feature bit exactly) is set, e.g.
> when deduplication feature is in use while fragments feature is not.  In
> this case, sbi->packed_inode could be NULL while fragments feature bit
> is set.
> 
> Fix this by accessing packed inode only when it exists.
> 
> Reported-by: syzbot+902d5a9373ae8f748a94 at syzkaller.appspotmail.com
> Link: https://syzkaller.appspot.com/bug?extid=902d5a9373ae8f748a94
> Fixes: 9e382914617c ("erofs: add helpers to load long xattr name prefixes")
> Signed-off-by: Jingbo Xu <jefflexu at linux.alibaba.com>

Reviewed-by: Yue Hu <huyue2 at coolpad.com>