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| author | Eric Dumazet <edumazet@google.com> | 2014-01-16 15:03:31 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-01-16 15:30:31 -0800 |
| commit | 0864c158836c2d0edb61f7128475e192b09bc851 (patch) | |
| tree | 8880646ac3da6b1ab7ff5b870e63475fcb6c0aa7 | |
| parent | 7967919db687f1a61e3d8fbf9f5582f01c8d2cf5 (diff) | |
| download | lwn-0864c158836c2d0edb61f7128475e192b09bc851.tar.gz lwn-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>
| -rw-r--r-- | net/ethernet/eth.c | 7 |
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); /* |