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net: gro: fix possible panic in skb_gro_receive() 

commit 2e71a6f808 (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>
This commit is contained in:
Eric Dumazet 2012-12-06 13:54:59 +00:00 committed by David S. Miller
parent 93b174ad71
commit c3c7c254b2
3 changed files with 8 additions and 3 deletions
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3
include/linux/netdevice.h
View File

@ -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)

2
net/core/dev.c
View File

@ -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;

6
net/core/skbuff.c
View File

@ -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: