| Message ID | alpine.LNX.2.00.1107171942400.32359@swampdragon.chaosbits.net |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
On 17.07.2011 19:46, Jesper Juhl wrote: > 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. > > Please review and commit if you believe this is correct. Thanks. > Looks correct, applied, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/ipv4/netfilter/ip_queue.c b/net/ipv4/netfilter/ip_queue.c index 5c9b9d9..48f7d5b 100644 --- a/net/ipv4/netfilter/ip_queue.c +++ b/net/ipv4/netfilter/ip_queue.c @@ -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; diff --git a/net/ipv6/netfilter/ip6_queue.c b/net/ipv6/netfilter/ip6_queue.c index 2493948..87b243a 100644 --- a/net/ipv6/netfilter/ip6_queue.c +++ b/net/ipv6/netfilter/ip6_queue.c @@ -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;
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. Please review and commit if you believe this is correct. Thanks. Signed-off-by: Jesper Juhl <jj@chaosbits.net> --- net/ipv4/netfilter/ip_queue.c | 1 + net/ipv6/netfilter/ip6_queue.c | 1 + 2 files changed, 2 insertions(+), 0 deletions(-) Disclaimer: Patch is compile tested only.