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Commit c3c7c254 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: gro: fix possible panic in skb_gro_receive() 



commit 2e71a6f8 (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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 93b174ad

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 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) 


	__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: