From df5f1b1a5b178eee5e420fb0ae49a1788ca7c59b Mon Sep 17 00:00:00 2001 From: Vivien Didelot Date: Wed, 9 Aug 2017 16:46:09 -0400 Subject: [PATCH] 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(-) diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c index fab41de8e9837..de66ca8e62017 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 */ -- 2.39.5