[PATCH net-next 2/8] netlink: Avoid netlink mmap alloc if msg size exceeds frame size
From: Thomas Graf <tgraf@suug.ch>
Date: 2013-11-21 18:13:50
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <tgraf@suug.ch> Reviewed-by: Daniel Borkmann <redacted> --- 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 bca50b9..6433489 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;
--
1.8.3.1