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Subject[PATCH 4.4 23/44] ALSA: rme9652: Hardening for potential Spectre v1
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@suse.de>

commit f526afcd8f71945c23ce581d7864ace93de8a4f7 upstream.

As recently Smatch suggested, one place in RME9652 driver may expand
the array directly from the user-space value with speculation:
sound/pci/rme9652/rme9652.c:2074 snd_rme9652_channel_info() warn: potential spectre issue 'rme9652->channel_map' (local cap)

This patch puts array_index_nospec() for hardening against it.

BugLink: https://marc.info/?l=linux-kernel&m=152411496503418&w=2
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/pci/rme9652/rme9652.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/sound/pci/rme9652/rme9652.c
+++ b/sound/pci/rme9652/rme9652.c
@@ -26,6 +26,7 @@
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/io.h>
+#include <linux/nospec.h>

#include <sound/core.h>
#include <sound/control.h>
@@ -2036,9 +2037,10 @@ static int snd_rme9652_channel_info(stru
if (snd_BUG_ON(info->channel >= RME9652_NCHANNELS))
return -EINVAL;

- if ((chn = rme9652->channel_map[info->channel]) < 0) {
+ chn = rme9652->channel_map[array_index_nospec(info->channel,
+ RME9652_NCHANNELS)];
+ if (chn < 0)
return -EINVAL;
- }

info->offset = chn * RME9652_CHANNEL_BUFFER_BYTES;
info->first = 0;

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