net: gro: fix possible panic in skb_gro_receive() (c3c7c254) · Commits · 戴 / test

commit (net: gro: selective flush of packets) added a bug for skbs using frag_list. This part of the GRO stack is rarely used, as it needs skb not using a page fragment for their skb->head. Most drivers do use a page fragment, but some of them use GFP_KERNEL allocations for the initial fill of their RX ring buffer. napi_gro_flush() overwrite skb->prev that was used for these skb to point to the last skb in frag_list. Fix this using a separate field in struct napi_gro_cb to point to the last fragment. Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -1488,6 +1488,9 @@ struct napi_gro_cb {

		/* Used in ipv6_gro_receive() */
		int proto;

		/* used in skb_gro_receive() slow path */
		struct sk_buff *last;
		};

		#define NAPI_GRO_CB(skb) ((struct napi_gro_cb *)(skb)->cb)

net/core/dev.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -3451,6 +3451,8 @@ static int napi_gro_complete(struct sk_buff *skb)
		struct list_head *head = &ptype_base[ntohs(type) & PTYPE_HASH_MASK];
		int err = -ENOENT;

		BUILD_BUG_ON(sizeof(struct napi_gro_cb) > sizeof(skb->cb));

		if (NAPI_GRO_CB(skb)->count == 1) {
		skb_shinfo(skb)->gso_size = 0;
		goto out;

net/core/skbuff.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -3004,7 +3004,7 @@ int skb_gro_receive(struct sk_buff *head, struct sk_buff skb)
		skb_shinfo(nskb)->gso_size = pinfo->gso_size;
		pinfo->gso_size = 0;
		skb_header_release(p);
		nskb->prev = p;
		NAPI_GRO_CB(nskb)->last = p;

		nskb->data_len += p->len;
		nskb->truesize += p->truesize;
		@@ -3030,8 +3030,8 @@ merge:

		__skb_pull(skb, offset);

		p->prev->next = skb;
		p->prev = skb;
		NAPI_GRO_CB(p)->last->next = skb;
		NAPI_GRO_CB(p)->last = skb;
		skb_header_release(skb);

		done:

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