Re: [PATCH] infiniband: avoid overflow warning

Bart Van Assche
2017-07-31T16:17:35Z

On Mon, 2017-07-31 at 18:04 +0200, Arnd Bergmann wrote:
> On Mon, Jul 31, 2017 at 5:32 PM, Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org> wrote:
> > So inetaddr_event() assigns AF_INET so .sin_family and gcc warns about code
> > that is only executed if .sin_family == AF_INET6? Since this warning is the
> > result of incorrect interprocedural analysis by gcc, shouldn't this be
> > reported as a bug to the gcc authors?
>
> I think the interprocedural analysis here is just a little worse than it could
> be, but it's not actually correct. It's not gcc that prints the warning (if
> it did, then I'd agree it would be a gcc bug) but the warning is triggered
> intentionally by the fortified version of memcpy in include/linux/string.h.
>
> The problem as I understand it is that gcc cannot guarantee that it
> tracks the value of addr->sa_family at least as far as the size of the
> stack object, and it has no strict reason to do so, so the inlined
> rdma_ip2gid() will still contain both cases.

Hello Arnd,

Had you already considered to uninline the rdma_ip2gid() function?

Bart.--