gro: Fix potential use after free (0da2afd5) · Commits · 戴 / test

The initial skb may have been freed after napi_gro_complete in napi_gro_receive if it was merged into an existing packet. Thus we cannot check same_flow (which indicates whether it was merged) after calling napi_gro_complete. This patch fixes this by saving the same_flow status before the call to napi_gro_complete. Signed-off-by:

Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/dev.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -2390,6 +2390,7 @@ int napi_gro_receive(struct napi_struct napi, struct sk_buff skb)
		__be16 type = skb->protocol;
		struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];
		int count = 0;
		int same_flow;
		int mac_len;

		if (!(skb->dev->features & NETIF_F_GRO))
		@@ -2425,6 +2426,8 @@ int napi_gro_receive(struct napi_struct napi, struct sk_buff skb)
		if (&ptype->list == head)
		goto normal;

		same_flow = NAPI_GRO_CB(skb)->same_flow;

		if (pp) {
		struct sk_buff nskb = pp;

		@@ -2434,7 +2437,7 @@ int napi_gro_receive(struct napi_struct napi, struct sk_buff skb)
		count--;
		}

		if (NAPI_GRO_CB(skb)->same_flow)
		if (same_flow)
		goto ok;

		if (NAPI_GRO_CB(skb)->flush \|\| count >= MAX_GRO_SKBS) {

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