[83/89] TOMOYO: Fix oops in tomoyo_mount_acl().

[Greg KH]

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

commit 4e78c724d47e2342aa8fde61f6b8536f662f795f upstream.

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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: James Morris <jmorris@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 security/tomoyo/mount.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/security/tomoyo/mount.c
+++ b/security/tomoyo/mount.c
@@ -138,7 +138,7 @@ static int tomoyo_mount_acl(struct tomoy
 	}
 	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;
 		}


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