From e71cb9e00922902ba0519f37d09145f117dc02b3 Mon Sep 17 00:00:00 2001 From: Vivien Didelot Date: Wed, 9 Aug 2017 16:46:09 -0400 Subject: net: dsa: ksz: fix skb freeing 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 Reviewed-by: Woojung Huh Signed-off-by: David S. Miller --- net/dsa/tag_ksz.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'net') diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c index fab41de8e983..de66ca8e6201 100644 --- a/net/dsa/tag_ksz.c +++ b/net/dsa/tag_ksz.c @@ -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 */ -- cgit v1.2.3