4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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.
Fixes: 158f323b9868 ("net: adjust skb->truesize in pskb_expand_head()") Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/ip_fragment.c | 5 +++++ 1 file changed, 5 insertions(+)
--- 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)