On Mon, Jul 31, 2017 at 2:10 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Mon, Jul 31, 2017 at 10:58 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: >> On Mon, Jul 31, 2017 at 12:30 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: >>> On Mon, Jul 31, 2017 at 9:08 AM, Moni Shoua <monis@xxxxxxxxxxxx> wrote: >>>>> break; >>>>> default: >>>>> return -EINVAL; >>>> what happens if you replace 16 with sizeof(struct in6_addr)? >>> >>> Same thing: the problem is that gcc already knows the size of the structure we >>> pass in here, and it is in fact shorter. >> >> So gcc is ignoring both the cast (to 16 byte struct in6_addr) and the >> caller's actual 128 byte struct sockaddr_storage, and looking only at >> struct sockaddr? That seems really weird. > > Using a sockaddr_storage on the stack would address the warning, but > the question was about just changing the hardcoded 16 to a sizeof() > operation, and that has no effect. Right, I didn't mean that; I was curious why the fortify macro resulted in an error at all. The callers are casting from struct sockaddr_storage (large enough) to struct sockaddr (not large enough), and then the inline is casting back to sockaddr_in6 (large enough). I would have expected fortify to check either sockaddr_storage or sockaddr_in6, but not sockaddr. -Kees -- Kees Cook Pixel Security -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
