From 90b476daa98d8c5dc1bb51dc2ee45efecdd12db6 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 30 Jul 2018 21:50:29 -0700 Subject: [PATCH] net: merge CVE-2018-5391 patch PD#172028 merge CVE patch ipv4: frags: handle possible skb truesize change [ Upstream commit 4672694bd4f1aebdab0ad763ae4716e89cb15221 ] ip_frag_queue() might call pskb_pull() on one skb that is already in the fragment queue. We need to take care of possible truesize change, or we might have an imbalance of the netns frags memory usage. IPv6 is immune to this bug, because RFC5722, Section 4, amended by Errata ID 3089 states : When reassembling an IPv6 datagram, if one or more its constituent fragments is determined to be an overlapping fragment, the entire datagram (and any constituent fragments) MUST be silently discarded. Change-Id: I55a7bb378c160972d99736e4ba592bc10c10f94e Fixes: 158f323b9868 ("net: adjust skb->truesize in pskb_expand_head()") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/ip_fragment.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 4bf3b8af0257..752711cd4834 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -446,11 +446,16 @@ found: int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ if (i < next->len) { + int delta = -next->truesize; + /* Eat head of the next overlapped fragment * and leave the loop. The next ones cannot overlap. */ if (!pskb_pull(next, i)) goto err; + delta += next->truesize; + if (delta) + add_frag_mem_limit(qp->q.net, delta); FRAG_CB(next)->offset += i; qp->q.meat -= i; if (next->ip_summed != CHECKSUM_UNNECESSARY)