On Thu, Sep 23, 2021 at 09:26:51AM +0200, Krzysztof Kozlowski wrote: > On 23/09/2021 08:50, Dan Carpenter wrote: > > This from static analysis inspired by CVE-2021-26708 where there was a > > race condition because it didn't lock_sock(sk) before saving > > "vsk->transport". Here it is saving "llcp_sock->local" but the concept > > is the same that it needs to take the lock first. > > I think the difference between this llcp_sock code and above transport, > is lack of writer to llcp_sock->local with whom you could race. > > Commits c0cfa2d8a788fcf4 and 6a2c0962105ae8ce causing the > multi-transport race show nicely assigns to vsk->transport when module > is unloaded. > > Here however there is no writer to llcp_sock->local, except bind and > connect and their error paths. The readers which you modify here, have > to happen after bind/connect. You cannot have getsockopt() or release() > before bind/connect, can you? Unless you mean here the bind error path, > where someone calls getsockopt() in the middle of bind()? Is it even > possible? > I don't know if this is a real issue either. Racing with bind would be harmless. The local pointer would be NULL and it would return harmlessly. You would have to race with release and have a third trying to release local devices. (Again that might be wild imagination. It may not be possible). regards, dan carpenter
