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rtnetlink: Fix message size calculation for link messages

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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>
This commit is contained in:
Thomas Graf 2010-11-11 15:47:59 +00:00 committed by David S. Miller
parent 8877870f8a
commit 369cf77a6a
1 changed files with 5 additions and 4 deletions
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9
net/core/rtnetlink.c
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@ -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;
}