netfilter: ip_queue: Fix small leak in ipq_build_packet_message()
authorJesper Juhl <jj@chaosbits.net>
Fri, 29 Jul 2011 14:38:49 +0000 (16:38 +0200)
committerPatrick McHardy <kaber@trash.net>
Fri, 29 Jul 2011 14:38:49 +0000 (16:38 +0200)
ipq_build_packet_message() in net/ipv4/netfilter/ip_queue.c and
net/ipv6/netfilter/ip6_queue.c contain a small potential mem leak as
far as I can tell.

We allocate memory for 'skb' with alloc_skb() annd then call
 nlh = NLMSG_PUT(skb, 0, 0, IPQM_PACKET, size - sizeof(*nlh));

NLMSG_PUT is a macro
 NLMSG_PUT(skb, pid, seq, type, len) \
   NLMSG_NEW(skb, pid, seq, type, len, 0)

that expands to NLMSG_NEW, which is also a macro which expands to:
 NLMSG_NEW(skb, pid, seq, type, len, flags) \
   ({ if (unlikely(skb_tailroom(skb) < (int)NLMSG_SPACE(len))) \
   goto nlmsg_failure; \
   __nlmsg_put(skb, pid, seq, type, len, flags); })

If we take the true branch of the 'if' statement and 'goto
nlmsg_failure', then we'll, at that point, return from
ipq_build_packet_message() without having assigned 'skb' to anything
and we'll leak the memory we allocated for it when it goes out of
scope.

Fix this by placing a 'kfree(skb)' at 'nlmsg_failure'.

I admit that I do not know how likely this to actually happen or even
if there's something that guarantees that it will never happen - I'm
not that familiar with this code, but if that is so, I've not been
able to spot it.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
net/ipv4/netfilter/ip_queue.c
net/ipv6/netfilter/ip6_queue.c

index 5c9b9d963918aa538086239d2351afea574324cb..48f7d5b4ff37adeb6687ade0649f7ed88aa7e688 100644 (file)
@@ -218,6 +218,7 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
        return skb;
 
 nlmsg_failure:
+       kfree_skb(skb);
        *errp = -EINVAL;
        printk(KERN_ERR "ip_queue: error creating packet message\n");
        return NULL;
index 249394863284bcb2edcb3228183a953393df1a26..87b243a25afa6688c09f16417bf697592071fac4 100644 (file)
@@ -218,6 +218,7 @@ ipq_build_packet_message(struct nf_queue_entry *entry, int *errp)
        return skb;
 
 nlmsg_failure:
+       kfree_skb(skb);
        *errp = -EINVAL;
        printk(KERN_ERR "ip6_queue: error creating packet message\n");
        return NULL;