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net: dsa: ksz: fix skb freeing

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The DSA layer frees the original skb when an xmit function returns NULL,
meaning an error occurred. But if the tagging code copied the original
skb, it is responsible of freeing the copy if an error occurs.

The ksz tagging code currently has two issues: if skb_put_padto fails,
the skb copy is not freed, and the original skb will be freed twice.

To fix that, move skb_put_padto inside both branches of the skb_tailroom
condition, before freeing the original skb, and free the copy on error.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Woojung Huh <woojung.huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vivien Didelot 2017-08-09 16:46:09 -04:00 committed by David S. Miller
parent 26273939ac
commit e71cb9e009
1 changed files with 9 additions and 4 deletions
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13
net/dsa/tag_ksz.c
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@ -42,6 +42,9 @@ 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))
return NULL;
nskb = skb;
} else {
nskb = alloc_skb(NET_IP_ALIGN + skb->len +
@ -56,13 +59,15 @@ static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev)
skb_set_transport_header(nskb,
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);
return NULL;
}
kfree_skb(skb);
}
/* skb is freed when it fails */
if (skb_put_padto(nskb, nskb->len + padlen))
return NULL;
tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
tag[0] = 0;
tag[1] = 1 << p->dp->index; /* destination port */