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

[Leann Ogasawara]

The following changes since commit 7fec2f29a52bd5c07921df6e0dc443de7ef5c9f4:
  Brad Figg (1):
        UBUNTU: Ubuntu-2.6.24-29.88

are available in the git repository at:

  git://kernel.ubuntu.com/ogasawara/ubuntu-hardy.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 757fccef9f476beb37e1571a193c309c4c71f6b1 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 a9c23b2..eac3c00 100644
--- a/sound/oss/soundcard.c
+++ b/sound/oss/soundcard.c
@@ -87,7 +87,7 @@ 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;
@@ -99,7 +99,7 @@ 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