Commit a7840259 authored by Gustavo A. R. Silva's avatar Gustavo A. R. Silva Committed by Juerg Haefliger

ALSA: pcm: Fix potential Spectre v1 vulnerability

BugLink: https://bugs.launchpad.net/bugs/1811647

commit 94ffb030 upstream.

stream is indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

sound/core/pcm.c:140 snd_pcm_control_ioctl() warn: potential spectre issue 'pcm->streams' [r] (local cap)

Fix this by sanitizing stream before using it to index pcm->streams

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJuerg Haefliger <juergh@canonical.com>
Signed-off-by: default avatarStefan Bader <stefan.bader@canonical.com>
parent f986e670
......@@ -25,6 +25,7 @@
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/nospec.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/pcm.h>
......@@ -125,6 +126,7 @@ static int snd_pcm_control_ioctl(struct snd_card *card,
return -EFAULT;
if (stream < 0 || stream > 1)
return -EINVAL;
stream = array_index_nospec(stream, 2);
if (get_user(subdevice, &info->subdevice))
return -EFAULT;
mutex_lock(&register_mutex);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment