47 lines
1.8 KiB
Diff
47 lines
1.8 KiB
Diff
From: Dan Rosenberg <drosenberg@vsecurity.com>
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Date: Tue, 28 Sep 2010 18:18:20 +0000 (-0400)
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Subject: ALSA: prevent heap corruption in snd_ctl_new()
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X-Git-Tag: v2.6.36-rc7~12^2~1
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftiwai%2Fsound-2.6.git;a=commitdiff_plain;h=5591bf07225523600450edd9e6ad258bb877b779
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ALSA: prevent heap corruption in snd_ctl_new()
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The snd_ctl_new() function in sound/core/control.c allocates space for a
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snd_kcontrol struct by performing arithmetic operations on a
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user-provided size without checking for integer overflow. If a user
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provides a large enough size, an overflow will occur, the allocated
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chunk will be too small, and a second user-influenced value will be
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written repeatedly past the bounds of this chunk. This code is
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reachable by unprivileged users who have permission to open
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a /dev/snd/controlC* device (on many distros, this is group "audio") via
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the SNDRV_CTL_IOCTL_ELEM_ADD and SNDRV_CTL_IOCTL_ELEM_REPLACE ioctls.
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Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
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Cc: <stable@kernel.org>
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Signed-off-by: Takashi Iwai <tiwai@suse.de>
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---
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diff --git a/sound/core/control.c b/sound/core/control.c
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index 070aab4..45a8180 100644
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--- a/sound/core/control.c
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+++ b/sound/core/control.c
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@@ -31,6 +31,7 @@
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/* max number of user-defined controls */
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#define MAX_USER_CONTROLS 32
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+#define MAX_CONTROL_COUNT 1028
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struct snd_kctl_ioctl {
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struct list_head list; /* list of all ioctls */
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@@ -195,6 +196,10 @@ static struct snd_kcontrol *snd_ctl_new(struct snd_kcontrol *control,
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if (snd_BUG_ON(!control || !control->count))
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return NULL;
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+
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+ if (control->count > MAX_CONTROL_COUNT)
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+ return NULL;
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+
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kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);
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if (kctl == NULL) {
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snd_printk(KERN_ERR "Cannot allocate control instance\n");
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