On Fri, May 26, 2017 at 01:17:10PM -0700, Kees Cook wrote: > This is another false positive in bad cast detection: > > net/unix/af_unix.c: In function ‘unix_skb_scm_eq’: > net/unix/af_unix.c:1621:31: note: found mismatched rhs struct pointer types: > ‘struct unix_skb_parms’ and ‘char’ > > const struct unix_skb_parms *u = &UNIXCB(skb); > ^ > > UNIXCB is: > > #define UNIXCB(skb) (*(struct unix_skb_parms *)&((skb)->cb)) > > And ->cb is: > > char cb[48] __aligned(8); > > This is a rather crazy cast, but appears to be safe in the face of > randomization, so whitelist it in the plugin.
We have a lot of network protocol that use the ->cb area, which makes me wonder why this one would be so special. It seems like everyone is just using a plain cast to a pointer without doing the address taking trick that doesn't make sense for arrays anyway. Maybe we just need to fix up the af_unix code to work the same as all other protocols?
