[3.11.y.z extended stable] Patch "audit: use nlmsg_len() to get message payload length" has been added to staging queue

[Luis Henriques]

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

    audit: use nlmsg_len() to get message payload length

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 96b5d5c2ddeb85bfa1eda37b4350f7125a43389b Mon Sep 17 00:00:00 2001
From: Mathias Krause <minipli at googlemail.com>
Date: Mon, 30 Sep 2013 22:04:25 +0200
Subject: audit: use nlmsg_len() to get message payload length

commit 4d8fe7376a12bf4524783dd95cbc00f1fece6232 upstream.

Using the nlmsg_len member of the netlink header to test if the message
is valid is wrong as it includes the size of the netlink header itself.
Thereby allowing to send short netlink messages that pass those checks.

Use nlmsg_len() instead to test for the right message length. The result
of nlmsg_len() is guaranteed to be non-negative as the netlink message
already passed the checks of nlmsg_ok().

Also switch to min_t() to please checkpatch.pl.

Cc: Al Viro <viro at zeniv.linux.org.uk>
Cc: Eric Paris <eparis at redhat.com>
Signed-off-by: Mathias Krause <minipli at googlemail.com>
Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
Signed-off-by: Eric Paris <eparis at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 kernel/audit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index d397a61..34eeb48 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -671,7 +671,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 				 &status_set, sizeof(status_set));
 		break;
 	case AUDIT_SET:
-		if (nlh->nlmsg_len < sizeof(struct audit_status))
+		if (nlmsg_len(nlh) < sizeof(struct audit_status))
 			return -EINVAL;
 		status_get   = (struct audit_status *)data;
 		if (status_get->mask & AUDIT_STATUS_ENABLED) {
@@ -833,7 +833,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)

 		memset(&s, 0, sizeof(s));
 		/* guard against past and future API changes */
-		memcpy(&s, data, min(sizeof(s), (size_t)nlh->nlmsg_len));
+		memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
 		if ((s.enabled != 0 && s.enabled != 1) ||
 		    (s.log_passwd != 0 && s.log_passwd != 1))
 			return -EINVAL;
--
1.8.3.2