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authorDan Rosenberg <drosenberg@vsecurity.com>2010-09-28 14:18:20 -0400
committerTakashi Iwai <tiwai@suse.de>2010-09-28 21:33:16 +0200
commit5591bf07225523600450edd9e6ad258bb877b779 (patch)
treef886a48ec51861e74c79eca3052adeb9646d1534 /sound
parente68d3b316ab7b02a074edc4f770e6a746390cb7d (diff)
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: Dan Rosenberg <drosenberg@vsecurity.com> Cc: <stable@kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound')
-rw-r--r--sound/core/control.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/sound/core/control.c b/sound/core/control.c
index 070aab490191..45a818002d99 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -31,6 +31,7 @@
/* max number of user-defined controls */
#define MAX_USER_CONTROLS 32
+#define MAX_CONTROL_COUNT 1028
struct snd_kctl_ioctl {
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))
return NULL;
+
+ if (control->count > MAX_CONTROL_COUNT)
+ return NULL;
+
kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);
if (kctl == NULL) {
snd_printk(KERN_ERR "Cannot allocate control instance\n");

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