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Commit 0da2afd5 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
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gro: Fix potential use after free 



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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84381345

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) {