* [PATCH] ALSA: pcm: Fix potential Spectre v1 vulnerability
@ 2018-12-12 21:36 Gustavo A. R. Silva
2018-12-13 8:15 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2018-12-12 21:36 UTC (permalink / raw)
To: Jaroslav Kysela, Takashi Iwai
Cc: alsa-devel, linux-kernel, Gustavo A. R. Silva
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=2
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
sound/core/pcm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index fdb9b92fc8d6..23141003a90d 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -32,6 +32,8 @@
#include <sound/control.h>
#include <sound/info.h>
+#include <linux/nospec.h>
+
#include "pcm_local.h"
MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>, Abramo Bagnara <abramo@alsa-project.org>");
@@ -129,6 +131,7 @@ 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(®ister_mutex);
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ALSA: pcm: Fix potential Spectre v1 vulnerability
2018-12-12 21:36 [PATCH] ALSA: pcm: Fix potential Spectre v1 vulnerability Gustavo A. R. Silva
@ 2018-12-13 8:15 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2018-12-13 8:15 UTC (permalink / raw)
To: Gustavo A. R. Silva ; +Cc: Jaroslav Kysela, alsa-devel, linux-kernel
On Wed, 12 Dec 2018 22:36:28 +0100,
Gustavo A. R. Silva wrote:
>
> 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=2
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Applied now (again after moving the include line into a more
appropriate place).
thanks,
Takashi
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