[ 16/82] rtnetlink: fix rtnl_calcit() and rtnl_dump_ifinfo()

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <eric.dumazet@xxxxxxxxx>

commit a4b64fbe482c7766f7925f03067fc637716bfa3f upstream.

nlmsg_parse() might return an error, so test its return value before
potential random memory accesses.

Errors introduced in commit 115c9b81928 (rtnetlink: Fix problem with
buffer allocation)

Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: Greg Rose <gregory.v.rose@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/core/rtnetlink.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 606a6e8..f965dce 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1060,11 +1060,12 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
 	rcu_read_lock();
 	cb->seq = net->dev_base_seq;
 
-	nlmsg_parse(cb->nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX,
-		    ifla_policy);
+	if (nlmsg_parse(cb->nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX,
+			ifla_policy) >= 0) {
 
-	if (tb[IFLA_EXT_MASK])
-		ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
+		if (tb[IFLA_EXT_MASK])
+			ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
+	}
 
 	for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
 		idx = 0;
@@ -1900,10 +1901,11 @@ static u16 rtnl_calcit(struct sk_buff *skb, struct nlmsghdr *nlh)
 	u32 ext_filter_mask = 0;
 	u16 min_ifinfo_dump_size = 0;
 
-	nlmsg_parse(nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX, ifla_policy);
-
-	if (tb[IFLA_EXT_MASK])
-		ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
+	if (nlmsg_parse(nlh, sizeof(struct rtgenmsg), tb, IFLA_MAX,
+			ifla_policy) >= 0) {
+		if (tb[IFLA_EXT_MASK])
+			ext_filter_mask = nla_get_u32(tb[IFLA_EXT_MASK]);
+	}
 
 	if (!ext_filter_mask)
 		return NLMSG_GOODSIZE;


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