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ALSA: hda: Hardening for potential Spectre v1 

As recently Smatch suggested, one place in HD-audio hwdep ioctl codes
may expand the array directly from the user-space value with
speculation:
  sound/pci/hda/hda_local.h:467 get_wcaps() warn: potential spectre issue 'codec->wcaps'

As get_wcaps() itself is a fairly frequently called inline function,
and there is only one single call with a user-space value, we replace
only the latter one to open-code locally with array_index_nospec()
hardening in this patch.

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>
This commit is contained in:
Takashi Iwai 2018-04-24 07:50:50 +02:00
parent 088e861edf
commit 69fa6f19b9
1 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
sound/pci/hda/hda_hwdep.c
View File

@ -21,6 +21,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/nospec.h>
#include <sound/core.h>
#include "hda_codec.h"
#include "hda_local.h"
@ -51,7 +52,16 @@ static int get_wcap_ioctl(struct hda_codec *codec,
if (get_user(verb, &arg->verb))
return -EFAULT;
res = get_wcaps(codec, verb >> 24);
/* open-code get_wcaps(verb>>24) with nospec */
verb >>= 24;
if (verb < codec->core.start_nid ||
verb >= codec->core.start_nid + codec->core.num_nodes) {
res = 0;
} else {
verb -= codec->core.start_nid;
verb = array_index_nospec(verb, codec->core.num_nodes);
res = codec->wcaps[verb];
}
if (put_user(res, &arg->res))
return -EFAULT;
return 0;