[CVE-2010-4527 Dapper] sound: Prevent buffer overflow in OSS load_mixer_volumes, CVE-2010-4527

[Leann Ogasawara]

The following changes since commit 2ce9a046a401ab70b7719085dd1b51e2f4a56a42:
  Brad Figg (1):
        UBUNTU: Ubuntu-2.6.15-57.95

are available in the git repository at:

  git://kernel.ubuntu.com/ogasawara/ubuntu-dapper.git CVE-2010-4527

Dan Rosenberg (1):
      sound: Prevent buffer overflow in OSS load_mixer_volumes, CVE-2010-4527

 sound/oss/soundcard.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

>From 9a0b6c4bd252c7888731071956e5ec904a6fa82c Mon Sep 17 00:00:00 2001
From: Dan Rosenberg <drosenberg at vsecurity.com>
Date: Sat, 25 Dec 2010 16:23:40 -0500
Subject: [PATCH] sound: Prevent buffer overflow in OSS load_mixer_volumes, CVE-2010-4527

CVE-2010-4527

BugLink: http://bugs.launchpad.net/bugs/737073

The load_mixer_volumes() function, which can be triggered by
unprivileged users via the SOUND_MIXER_SETLEVELS ioctl, is vulnerable to
a buffer overflow.  Because the provided "name" argument isn't
guaranteed to be NULL terminated at the expected 32 bytes, it's possible
to overflow past the end of the last element in the mixer_vols array.
Further exploitation can result in an arbitrary kernel write (via
subsequent calls to load_mixer_volumes()) leading to privilege
escalation, or arbitrary kernel reads via get_mixer_levels().  In
addition, the strcmp() may leak bytes beyond the mixer_vols array.

Signed-off-by: Dan Rosenberg <drosenberg at vsecurity.com>
Cc: stable <stable at kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
(cherry picked from commit d81a12bc29ae4038770e05dce4ab7f26fd5880fb)

Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
---
 sound/oss/soundcard.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/oss/soundcard.c b/sound/oss/soundcard.c
index d33bb46..4f12363 100644
--- a/sound/oss/soundcard.c
+++ b/sound/oss/soundcard.c
@@ -86,7 +86,7 @@ int *load_mixer_volumes(char *name, int *levels, int present)
 	int             i, n;
 
 	for (i = 0; i < num_mixer_volumes; i++) {
-		if (strcmp(name, mixer_vols[i].name) == 0) {
+		if (strncmp(name, mixer_vols[i].name, 32) == 0) {
 			if (present)
 				mixer_vols[i].num = i;
 			return mixer_vols[i].levels;
@@ -98,7 +98,7 @@ int *load_mixer_volumes(char *name, int *levels, int present)
 	}
 	n = num_mixer_volumes++;
 
-	strcpy(mixer_vols[n].name, name);
+	strncpy(mixer_vols[n].name, name, 32);
 
 	if (present)
 		mixer_vols[n].num = n;
-- 
1.7.0.4