On Fri, Nov 15, 2024 at 01:06:15PM +0000, Al Viro wrote: > 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. BTW, seeing that ntfs doesn't even touch ->i_link, you are dealing with aftermath of memory corruption, so it's definitely papering over the actual bug here.
