On Fri, 25 Aug 2017 09:52:17 +0200
Steffen Klassert <steffen.klass...@secunet.com> wrote:
> On Fri, Aug 25, 2017 at 09:05:42AM +0200, Steffen Klassert wrote:
> > rt_cookie might be used uninitialized, fix this by
> > initializing it.
> >
> > Fixes: c5cff8561d2d ("ipv6: add rcu grace period before freeing fib6_node")
> > Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
> > ---
> > net/ipv6/route.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index a9d3564..48c8c92 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -1289,7 +1289,7 @@ static void rt6_dst_from_metrics_check(struct
> > rt6_info *rt)
> >
> > static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie)
> > {
> > - u32 rt_cookie;
> > + u32 rt_cookie = 0;
> >
> > if (!rt6_get_cookie_safe(rt, &rt_cookie) || rt_cookie != cookie)
> > return NULL;
>
> The compiler warning seems to be a false positive, as
> rt_cookie != cookie is only checked if rt6_get_cookie_safe
> returns true in which case rt_cookie is initialized.
>
> Please disregard this patch.
...or not? I was thinking of sending a similar patch with
uninitialized_var(rt_cookie), but it seems we have similar cases
where we just initialize to zero instead.
I wonder which approach is considered the most acceptable nowadays. I
would be in favour of uninitialized_var() as it doesn't change the
binary output, but https://lwn.net/Articles/529954/ also contains some
valid criticism. Ideas?
--
Stefano
