Re: [PATCH net] net: socket: set sock->sk to NULL after calling proto_ops::release()

[Eric Dumazet]

On 02/22/2019 09:57 AM, Eric Biggers wrote:

> ->setattr() is called under inode_lock(), which __sock_release() also takes.  So
> the uses of sock->sk are serialized.  See commit 6d8c50dcb029 ("socket: close
> race condition between sock_close() and sockfs_setattr()").

Oh right, we added another inode_lock()/inode_unlock() for sock_close()


> 
> The issue now is that if ->setattr() happens *after* __sock_release() (which is
> possible if fchownat() gets the reference to the file's 'struct path', then the
> file is close()d by another thread, then fchownat() continues), it will see
> stale sock->sk because for many socket types it wasn't set to NULL earlier.
> 
> - Eric
>