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Commit 5591bf07 authored by Dan Rosenberg's avatar Dan Rosenberg Committed by Takashi Iwai
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ALSA: prevent heap corruption in snd_ctl_new() 



The snd_ctl_new() function in sound/core/control.c allocates space for a
snd_kcontrol struct by performing arithmetic operations on a
user-provided size without checking for integer overflow.  If a user
provides a large enough size, an overflow will occur, the allocated
chunk will be too small, and a second user-influenced value will be
written repeatedly past the bounds of this chunk.  This code is
reachable by unprivileged users who have permission to open
a /dev/snd/controlC* device (on many distros, this is group "audio") via
the SNDRV_CTL_IOCTL_ELEM_ADD and SNDRV_CTL_IOCTL_ELEM_REPLACE ioctls.

Signed-off-by: default avatarDan Rosenberg <drosenberg@vsecurity.com>
Cc: <stable@kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e68d3b31

sound/core/control.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -31,6 +31,7 @@ 




/* max number of user-defined controls */

/* max number of user-defined controls */

#define MAX_USER_CONTROLS	32

#define MAX_USER_CONTROLS	32

#define MAX_CONTROL_COUNT	1028





struct snd_kctl_ioctl {

struct snd_kctl_ioctl {

	struct list_head list;		/* list of all ioctls */

	struct list_head list;		/* list of all ioctls */
@@ -195,6 +196,10 @@ static struct snd_kcontrol *snd_ctl_new(struct snd_kcontrol *control, 
	

	

	if (snd_BUG_ON(!control || !control->count))

	if (snd_BUG_ON(!control || !control->count))

		return NULL;

		return NULL;



	if (control->count > MAX_CONTROL_COUNT)

		return NULL;



	kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);

	kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);

	if (kctl == NULL) {

	if (kctl == NULL) {

		snd_printk(KERN_ERR "Cannot allocate control instance\n");

		snd_printk(KERN_ERR "Cannot allocate control instance\n");