[natty, natty/ti-omap4 CVE 1/1] TOMOYO: Fix oops in tomoyo_mount_acl().

[Andy Whitcroft]

From: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>

In tomoyo_mount_acl() since 2.6.36, kern_path() was called without checking
dev_name != NULL. As a result, an unprivileged user can trigger oops by issuing
mount(NULL, "/", "ext3", 0, NULL) request.
Fix this by checking dev_name != NULL before calling kern_path(dev_name).

Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Cc: stable at kernel.org
Signed-off-by: James Morris <jmorris at namei.org>

(cherry picked from commit 4e78c724d47e2342aa8fde61f6b8536f662f795f)
CVE-2011-2518
BugLink: http://bugs.launchpad.net/bugs/922377
Signed-off-by: Andy Whitcroft <apw at canonical.com>
---
 security/tomoyo/mount.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/security/tomoyo/mount.c b/security/tomoyo/mount.c
index 82bf8c2..afa07cf 100644
--- a/security/tomoyo/mount.c
+++ b/security/tomoyo/mount.c
@@ -138,7 +138,7 @@ static int tomoyo_mount_acl(struct tomoyo_request_info *r, char *dev_name,
 	}
 	if (need_dev) {
 		/* Get mount point or device file. */
-		if (kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
+		if (!dev_name || kern_path(dev_name, LOOKUP_FOLLOW, &path)) {
 			error = -ENOENT;
 			goto out;
 		}
-- 
1.7.8.3