[3.16.y-ckt stable] Patch "svcrpc: fix memory leak in gssp_accept_sec_context_upcall" has been added to staging queue

[Luis Henriques]

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

    svcrpc: fix memory leak in gssp_accept_sec_context_upcall

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?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-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.
-Luis

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>From ee0edc3e42023ff9cda53ec2dfa5d7b8802ac0b5 Mon Sep 17 00:00:00 2001
From: David Ramos <daramos at stanford.edu>
Date: Fri, 13 Feb 2015 13:11:51 -0800
Subject: svcrpc: fix memory leak in gssp_accept_sec_context_upcall
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit a1d1e9be5a1dafe0ddc2181a9201c2ae29c71eff upstream.

Our UC-KLEE tool found a kernel memory leak of 512 bytes (on x86_64) for
each call to gssp_accept_sec_context_upcall()
(net/sunrpc/auth_gss/gss_rpc_upcall.c). Since it appears that this call
can be triggered by remote connections (at least, from a cursory a
glance at the call chain), it may be exploitable to cause kernel memory
exhaustion. We found the bug in kernel 3.16.3, but it appears to date
back to commit 9dfd87da1aeb0fd364167ad199f40fe96a6a87be (2013-08-20).

The gssp_accept_sec_context_upcall() function performs a pair of calls
to gssp_alloc_receive_pages() and gssp_free_receive_pages().  The first
allocates memory for arg->pages.  The second then frees the pages
pointed to by the arg->pages array, but not the array itself.

Reported-by: David A. Ramos <daramos at stanford.edu>
Fixes: 9dfd87da1aeb ("rpc: fix huge kmalloc's in gss-proxy”)
Signed-off-by: David A. Ramos <daramos at stanford.edu>
Signed-off-by: J. Bruce Fields <bfields at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/sunrpc/auth_gss/gss_rpc_upcall.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sunrpc/auth_gss/gss_rpc_upcall.c b/net/sunrpc/auth_gss/gss_rpc_upcall.c
index abbb7dcd1689..59eeed43eda2 100644
--- a/net/sunrpc/auth_gss/gss_rpc_upcall.c
+++ b/net/sunrpc/auth_gss/gss_rpc_upcall.c
@@ -217,6 +217,8 @@ static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)

 	for (i = 0; i < arg->npages && arg->pages[i]; i++)
 		__free_page(arg->pages[i]);
+
+	kfree(arg->pages);
 }

 static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)