Commit 4db79a32 authored by Sabrina Dubroca's avatar Sabrina Dubroca Committed by Jakub Kicinski
Browse files

net: gro: don't merge zcopy skbs 



skb_gro_receive() can currently copy frags between the source and GRO
skb, without checking the zerocopy status, and in particular the
SKBFL_MANAGED_FRAG_REFS flag.

When SKBFL_MANAGED_FRAG_REFS is set, the skb doesn't hold a reference
on the pages in shinfo->frags. Appending those frags to another skb's
frags without fixing up the page refcount can lead to UAF.

When either the last skb in the GRO chain (the one we would append
frags to) or the source skb is zerocopy, don't merge the skbs.

Fixes: 753f1ca4 ("net: introduce managed frags infrastructure")
Reported-by: default avatarHuzaifa Sidhpurwala <huzaifas@redhat.com>
Signed-off-by: default avatarSabrina Dubroca <sd@queasysnail.net>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/c3b7f906bbfcbdfd7b4fa9d6c18a438870df85be.1779307748.git.sd@queasysnail.net


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 3d4432d3

net/core/gro.c

+3 −0
Original line number Diff line number Diff line
@@ -109,6 +109,9 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb) 
	if (p->pp_recycle != skb->pp_recycle)

		return -ETOOMANYREFS;



	if (skb_zcopy(p) || skb_zcopy(skb))

		return -ETOOMANYREFS;



	if (unlikely(p->len + len >= netif_get_gro_max_size(p->dev, p) ||

		     NAPI_GRO_CB(skb)->flush))

		return -E2BIG;