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Message-Id: <21435b02616aca6f1442d343e53b69abc2d88b4d.1385137618.git.tgraf@suug.ch> Date: Fri, 22 Nov 2013 17:56:05 +0100 From: Thomas Graf <tgraf@...g.ch> To: jesse@...ira.com, davem@...emloft.net Cc: dev@...nvswitch.org, netdev@...r.kernel.org, dborkman@...hat.com, ffusco@...hat.com, fleitner@...hat.com, eric.dumazet@...il.com, bhutchings@...arflare.com Subject: [PATCH net-next 2/8] 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 <tgraf@...g.ch> Reviewed-by: Daniel Borkmann <dborkman@...hat.com> --- 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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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