[3.16.y-ckt stable] Patch "fib_rules: fix fib rule dumps across multiple skbs" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    fib_rules: fix fib rule dumps across multiple skbs

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.19.8-ckt9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 4c0c4ca6e91139a7d4024f6f186179ed4f292bd4 Mon Sep 17 00:00:00 2001
From: Wilson Kok <wkok at cumulusnetworks.com>
Date: Tue, 22 Sep 2015 21:40:22 -0700
Subject: fib_rules: fix fib rule dumps across multiple skbs

commit 41fc014332d91ee90c32840bf161f9685b7fbf2b upstream.

dump_rules returns skb length and not error.
But when family == AF_UNSPEC, the caller of dump_rules
assumes that it returns an error. Hence, when family == AF_UNSPEC,
we continue trying to dump on -EMSGSIZE errors resulting in
incorrect dump idx carried between skbs belonging to the same dump.
This results in fib rule dump always only dumping rules that fit
into the first skb.

This patch fixes dump_rules to return error so that we exit correctly
and idx is correctly maintained between skbs that are part of the
same dump.

Signed-off-by: Wilson Kok <wkok at cumulusnetworks.com>
Signed-off-by: Roopa Prabhu <roopa at cumulusnetworks.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/core/fib_rules.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 185c341..aeedc3a 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -621,15 +621,17 @@ static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
 {
 	int idx = 0;
 	struct fib_rule *rule;
+	int err = 0;

 	rcu_read_lock();
 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 		if (idx < cb->args[1])
 			goto skip;

-		if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).portid,
-				     cb->nlh->nlmsg_seq, RTM_NEWRULE,
-				     NLM_F_MULTI, ops) < 0)
+		err = fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).portid,
+				       cb->nlh->nlmsg_seq, RTM_NEWRULE,
+				       NLM_F_MULTI, ops);
+		if (err)
 			break;
 skip:
 		idx++;
@@ -638,7 +640,7 @@ skip:
 	cb->args[1] = idx;
 	rules_ops_put(ops);

-	return skb->len;
+	return err;
 }

 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
@@ -654,7 +656,9 @@ static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
 		if (ops == NULL)
 			return -EAFNOSUPPORT;

-		return dump_rules(skb, cb, ops);
+		dump_rules(skb, cb, ops);
+
+		return skb->len;
 	}

 	rcu_read_lock();
--
1.9.1