korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-14 15:54:15 +08:00
Code Issues Packages Projects Releases Wiki Activity

net: drop skb on failure in ip_check_defrag()

Browse Source 
[ Upstream commit 7de414a9dd ]

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 88078d98d1, 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: 88078d98d1 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Cong Wang 2018-11-01 12:02:37 -07:00 committed by Greg Kroah-Hartman
parent fd090ba395
commit 623670a9f2
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/ipv4/ip_fragment.c
View File

@ -720,10 +720,14 @@ 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;