Re: [PATCH] fs: add check for symlink corrupted

[Al Viro]

On Fri, Nov 15, 2024 at 05:49:08PM +0800, Lizhi Xu wrote:
> syzbot reported a null-ptr-deref in pick_link. [1]
> When symlink's inode is corrupted, the value of the i_link is 2 in this case,
> it will trigger null pointer deref when accessing *res in pick_link(). 
> 
> To avoid this issue, add a check for inode mode, return -EINVAL when it's
> not symlink.

NAK.  Don't paper over filesystem bugs at pathwalk time - it's the wrong
place for that.  Fix it at in-core inode creation time.