RE: [PATCH] rtnetlink: fix rtnl_calcit() and rtnl_dump_ifinfo()

-----Original Message-----
From: Eric Dumazet [mailto:eric.dumazet@gmail.com]
Sent: Sunday, March 04, 2012 2:32 PM
To: David Miller
Cc: Rose, Gregory V; netdev@vger.kernel.org
Subject: [PATCH] rtnetlink: fix rtnl_calcit() and rtnl_dump_ifinfo()

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 <redacted>
Cc: Greg Rose <redacted>
---
 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;