On Thu, Dec 01, 2016 at 06:34:07AM -0800, Eric Dumazet wrote:
> On Thu, 2016-12-01 at 14:06 +0100, Artem Savkov wrote:
> > segs needs to be checked for being NULL in ipv6_gso_segment() before calling
> > skb_shinfo(segs), otherwise kernel can run into a NULL-pointer dereference:
> > Signed-off-by: Artem Savkov <asav...@redhat.com>
> > ---
> > diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
> > index 1fcf61f..89c59e6 100644
> > --- a/net/ipv6/ip6_offload.c
> > +++ b/net/ipv6/ip6_offload.c
> > @@ -99,7 +99,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff
> > *skb,
> > segs = ops->callbacks.gso_segment(skb, features);
> > }
> > - if (IS_ERR(segs))
> > + if (IS_ERR_OR_NULL(segs))
> > goto out;
> > gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
> Do you know when was this bug added ?
It started to show up with 4.9-rc4, from what I see the culprit is
07b26c9 gso: Support partial splitting at the frag_list pointer
> Are you sure this is the right fix ?
I am not, but this would have the same behavior as pre-07b26c9 code and
IS_ERR_OR_NULL is used in ipv4's inet_gso_segment().
> Which gso_segment() is returning NULL exactly ?
Unfortunatelly I don't know that and I don't have a good reproducer, the
only way to reproduce this that I currently have is calling