path: root/net/ipv4/ip_fragment.c
diff options
authorCong Wang <xiyou.wangcong@gmail.com>2018-11-01 12:02:37 -0700
committerDavid S. Miller <davem@davemloft.net>2018-11-01 13:55:30 -0700
commit7de414a9dd91426318df7b63da024b2b07e53df5 (patch)
treeb1b64a2bffe25c4c250465e3bcd45d21f1dca1ba /net/ipv4/ip_fragment.c
parentMerge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux (diff)
net: drop skb on failure in ip_check_defrag()
Most callers of pskb_trim_rcsum() simply drop the skb when it fails, however, ip_check_defrag() still continues to pass the skb up to stack. This is suspicious. In ip_check_defrag(), after we learn the skb is an IP fragment, passing the skb to callers makes no sense, because callers expect fragments are defrag'ed on success. So, dropping the skb when we can't defrag it is reasonable. Note, prior to commit 88078d98d1bb, this is not a big problem as checksum will be fixed up anyway. After it, the checksum is not correct on failure. Found this during code review. Fixes: 88078d98d1bb ("net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends") Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 8 insertions, 4 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 9b0158fa431f..d6ee343fdb86 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -722,10 +722,14 @@ struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
if (ip_is_fragment(&iph)) {
skb = skb_share_check(skb, GFP_ATOMIC);
if (skb) {
- if (!pskb_may_pull(skb, netoff + iph.ihl * 4))
- return skb;
- if (pskb_trim_rcsum(skb, netoff + len))
- return skb;
+ if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) {
+ kfree_skb(skb);
+ return NULL;
+ }
+ if (pskb_trim_rcsum(skb, netoff + len)) {
+ kfree_skb(skb);
+ return NULL;
+ }
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
if (ip_defrag(net, skb, user))
return NULL;