From 563bca879a039771c666a03965e14d10989a5b07 Mon Sep 17 00:00:00 2001
From: Yevgeny Pats <yevgeny@perception-point.io>
Date: Tue, 19 Jan 2016 22:09:04 +0000
Subject: UPSTREAM: KEYS: Fix keyring ref leak in join_session_keyring()

(cherry pick from commit 23567fd052a9abb6d67fe8e7a9ccdd9800a540f2)

This fixes CVE-2016-0728.

If a thread is asked to join as a session keyring the keyring that's already
set as its session, we leak a keyring reference.

This can be tested with the following program:

	#include <stddef.h>
	#include <stdio.h>
	#include <sys/types.h>
	#include <keyutils.h>

	int main(int argc, const char *argv[])
	{
		int i = 0;
		key_serial_t serial;

		serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
				"leaked-keyring");
		if (serial < 0) {
			perror("keyctl");
			return -1;
		}

		if (keyctl(KEYCTL_SETPERM, serial,
			   KEY_POS_ALL | KEY_USR_ALL) < 0) {
			perror("keyctl");
			return -1;
		}

		for (i = 0; i < 100; i++) {
			serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
					"leaked-keyring");
			if (serial < 0) {
				perror("keyctl");
				return -1;
			}
		}

		return 0;
	}

If, after the program has run, there something like the following line in
/proc/keys:

3f3d898f I--Q---   100 perm 3f3f0000     0     0 keyring   leaked-keyring: empty

with a usage count of 100 * the number of times the program has been run,
then the kernel is malfunctioning.  If leaked-keyring has zero usages or
has been garbage collected, then the problem is fixed.

Bug 1720836

Reported-by: Yevgeny Pats <yevgeny@perception-point.io>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Change-Id: I10177a58a7b3178eda95017557edaa7298594d06
(cherry picked from commit 9fc5f368bb89b65b591c4f800dfbcc7432e49de5)
Signed-off-by: Sumit Singh <sumsingh@nvidia.com>
Reviewed-on: http://git-master/r/935565
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
(cherry picked from commit 07be7f19b4c356ce94642d0c2cecb93179a9a9bc)
Signed-off-by: Bibek Basu <bbasu@nvidia.com>
Reviewed-on: http://git-master/r/1210637
Reviewed-by: Jeetesh Burman <jburman@nvidia.com>
---
 security/keys/process_keys.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'security')

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 42defae1e161..cd871dc8b7c0 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -792,6 +792,7 @@ long join_session_keyring(const char *name)
 		ret = PTR_ERR(keyring);
 		goto error2;
 	} else if (keyring == new->session_keyring) {
+		key_put(keyring);
 		ret = 0;
 		goto error2;
 	}
-- 
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