From aae9f0e22c07f6b97752741156ac0b3637d37a1a Mon Sep 17 00:00:00 2001 From: Thomas Graf Date: Sat, 30 Nov 2013 13:21:31 +0100 Subject: [PATCH] netlink: Avoid netlink mmap alloc if msg size exceeds frame size An insufficent ring frame size configuration can lead to an unnecessary skb allocation for every Netlink message. Check frame size before taking the queue lock and allocating the skb and re-check with lock to be safe. Signed-off-by: Thomas Graf Reviewed-by: Daniel Borkmann Signed-off-by: Jesse Gross --- net/netlink/af_netlink.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index bca50b95c182..64334893c61c 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -1769,6 +1769,9 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size, if (ring->pg_vec == NULL) goto out_put; + if (ring->frame_size - NL_MMAP_HDRLEN < size) + goto out_put; + skb = alloc_skb_head(gfp_mask); if (skb == NULL) goto err1; @@ -1778,6 +1781,7 @@ struct sk_buff *netlink_alloc_skb(struct sock *ssk, unsigned int size, if (ring->pg_vec == NULL) goto out_free; + /* check again under lock */ maxlen = ring->frame_size - NL_MMAP_HDRLEN; if (maxlen < size) goto out_free; -- 2.11.0