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netlink: Avoid netlink mmap alloc if msg size exceeds frame size

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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 <dborkman@redhat.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
This commit is contained in:
Thomas Graf 2013-11-30 13:21:31 +01:00 committed by Jesse Gross
parent bb9b18fb55
commit aae9f0e22c
1 changed files with 4 additions and 0 deletions
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4
net/netlink/af_netlink.c
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@ -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;