Commit 369cf77a authored Nov 11, 2010 by Thomas Graf Committed by David S. Miller Nov 12, 2010

rtnetlink: Fix message size calculation for link messages



nlmsg_total_size() calculates the length of a netlink message
including header and alignment. nla_total_size() calculates the
space an individual attribute consumes which was meant to be used
in this context.

Also, ensure to account for the attribute header for the
IFLA_INFO_XSTATS attribute as implementations of get_xstats_size()
seem to assume that we do so.

The addition of two message headers minus the missing attribute
header resulted in a calculated message size that was larger than
required. Therefore we never risked running out of skb tailroom.

Signed-off-by: Thomas Graf <tgraf@infradead.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 8877870f

net/core/rtnetlink.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -347,16 +347,17 @@ static size_t rtnl_link_get_size(const struct net_device *dev)
		if (!ops)
		return 0;

		size = nlmsg_total_size(sizeof(struct nlattr)) + /* IFLA_LINKINFO */
		nlmsg_total_size(strlen(ops->kind) + 1); /* IFLA_INFO_KIND */
		size = nla_total_size(sizeof(struct nlattr)) + /* IFLA_LINKINFO */
		nla_total_size(strlen(ops->kind) + 1); /* IFLA_INFO_KIND */

		if (ops->get_size)
		/* IFLA_INFO_DATA + nested data */
		size += nlmsg_total_size(sizeof(struct nlattr)) +
		size += nla_total_size(sizeof(struct nlattr)) +
		ops->get_size(dev);

		if (ops->get_xstats_size)
		size += ops->get_xstats_size(dev); /* IFLA_INFO_XSTATS */
		/* IFLA_INFO_XSTATS */
		size += nla_total_size(ops->get_xstats_size(dev));

		return size;
		}