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net: gro: fix a potential crash in skb_gro_reset_offset 

Before accessing skb first fragment, better make sure there
is one.

This is probably not needed for old kernels, since an ethernet frame
cannot contain only an ethernet header, but the recent GRO addition
to tunnels makes this patch needed.

Also skb_gro_reset_offset() can be static, it actually allows
compiler to inline it.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-10-06 22:28:06 +00:00 committed by David S. Miller
parent 51ec04038c
commit ca07e43e28
2 changed files with 8 additions and 7 deletions
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1
include/linux/netdevice.h
View File

@ -1663,7 +1663,6 @@ extern int netpoll_trap(void);
#endif
extern int skb_gro_receive(struct sk_buff **head,
struct sk_buff *skb);
extern void skb_gro_reset_offset(struct sk_buff *skb);
static inline unsigned int skb_gro_offset(const struct sk_buff *skb)
{

14
net/core/dev.c
View File

@ -3631,20 +3631,22 @@ gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
}
EXPORT_SYMBOL(napi_skb_finish);
void skb_gro_reset_offset(struct sk_buff *skb)
static void skb_gro_reset_offset(struct sk_buff *skb)
{
const struct skb_shared_info *pinfo = skb_shinfo(skb);
const skb_frag_t *frag0 = &pinfo->frags[0];
NAPI_GRO_CB(skb)->data_offset = 0;
NAPI_GRO_CB(skb)->frag0 = NULL;
NAPI_GRO_CB(skb)->frag0_len = 0;
if (skb->mac_header == skb->tail &&
!PageHighMem(skb_frag_page(&skb_shinfo(skb)->frags[0]))) {
NAPI_GRO_CB(skb)->frag0 =
skb_frag_address(&skb_shinfo(skb)->frags[0]);
NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(&skb_shinfo(skb)->frags[0]);
pinfo->nr_frags &&
!PageHighMem(skb_frag_page(frag0))) {
NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
NAPI_GRO_CB(skb)->frag0_len = skb_frag_size(frag0);
}
}
EXPORT_SYMBOL(skb_gro_reset_offset);
gro_result_t napi_gro_receive(struct napi_struct *napi, struct sk_buff *skb)
{