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net: dsa: skb_put_padto() already frees nskb 

The first call of skb_put_padto() will free up the SKB on error, but we
return NULL which tells dsa_slave_xmit() that the original SKB should be
freed so this would lead to a double free here.

The second skb_put_padto() already frees the passed sk_buff reference
upon error, so calling kfree_skb() on it again is not necessary.

Detected by CoverityScan, CID#1416687 ("USE_AFTER_FREE")

Fixes: e71cb9e009 ("net: dsa: ksz: fix skb freeing")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
zero-colors
Florian Fainelli 2017-08-22 15:12:15 -07:00 committed by David S. Miller
parent cd0a137acb
commit 4971667924
1 changed files with 6 additions and 4 deletions
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10
net/dsa/tag_ksz.c
View File

@ -42,7 +42,8 @@ static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
if (skb_tailroom(skb) >= padlen + KSZ_INGRESS_TAG_LEN) {
if (skb_put_padto(skb, skb->len + padlen))
/* Let dsa_slave_xmit() free skb */
if (__skb_put_padto(skb, skb->len + padlen, false))
return NULL;
nskb = skb;
@ -60,10 +61,11 @@ static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
skb_transport_header(skb) - skb->head);
skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
if (skb_put_padto(nskb, nskb->len + padlen)) {
kfree_skb(nskb);
/* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
* skb
*/
if (skb_put_padto(nskb, nskb->len + padlen))
return NULL;
}
kfree_skb(skb);
}