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authorEric Dumazet <edumazet@google.com>2014-01-16 15:03:31 -0800
committerDavid S. Miller <davem@davemloft.net>2014-01-16 15:30:31 -0800
commit0864c158836c2d0edb61f7128475e192b09bc851 (patch)
tree8880646ac3da6b1ab7ff5b870e63475fcb6c0aa7 /net/ethernet
parentMerge branch 'stmmac_pm' (diff)
downloadlinux-dev-0864c158836c2d0edb61f7128475e192b09bc851.tar.xz
linux-dev-0864c158836c2d0edb61f7128475e192b09bc851.zip
net: eth_type_trans() should use skb_header_pointer()
eth_type_trans() can read uninitialized memory as drivers do not necessarily pull more than 14 bytes in skb->head before calling it. As David suggested, we can use skb_header_pointer() to fix this without breaking some drivers that might not expect eth_type_trans() pulling 2 additional bytes. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ethernet')
-rw-r--r--net/ethernet/eth.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 8f032bae60ad..5dc638cad2e1 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -156,7 +156,9 @@ EXPORT_SYMBOL(eth_rebuild_header);
*/
__be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
{
- struct ethhdr *eth;
+ unsigned short _service_access_point;
+ const unsigned short *sap;
+ const struct ethhdr *eth;
skb->dev = dev;
skb_reset_mac_header(skb);
@@ -194,7 +196,8 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
* layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
* won't work for fault tolerant netware but does for the rest.
*/
- if (unlikely(skb->len >= 2 && *(unsigned short *)(skb->data) == 0xFFFF))
+ sap = skb_header_pointer(skb, 0, sizeof(*sap), &_service_access_point);
+ if (sap && *sap == 0xFFFF)
return htons(ETH_P_802_3);
/*