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authorTakashi Iwai <tiwai@suse.de>2018-04-24 07:45:56 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-05-02 07:53:41 -0700
commit210392f6093fa65483a25a77d4397f1654c067bd (patch)
tree1c9e62564fcbdce611b40b469d04be653efb5bc7
parent4984b8bb89fc7d0f0415b4a48fc07333f7b7bbca (diff)
ALSA: control: Hardening for potential Spectre v1
commit 088e861edffb84879cf0c0d1b02eda078c3a0ffe upstream. As recently Smatch suggested, a few places in ALSA control core codes may expand the array directly from the user-space value with speculation: sound/core/control.c:1003 snd_ctl_elem_lock() warn: potential spectre issue 'kctl->vd' sound/core/control.c:1031 snd_ctl_elem_unlock() warn: potential spectre issue 'kctl->vd' sound/core/control.c:844 snd_ctl_elem_info() warn: potential spectre issue 'kctl->vd' sound/core/control.c:891 snd_ctl_elem_read() warn: potential spectre issue 'kctl->vd' sound/core/control.c:939 snd_ctl_elem_write() warn: potential spectre issue 'kctl->vd' Although all these seem doing only the first load without further reference, we may want to stay in a safer side, so hardening with array_index_nospec() would still make sense. In this patch, we put array_index_nospec() to the common snd_ctl_get_ioff*() helpers instead of each caller. These helpers are also referred from some drivers, too, and basically all usages are to calculate the array index from the user-space value, hence it's better to cover there. 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>
-rw-r--r--include/sound/control.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/include/sound/control.h b/include/sound/control.h
index 21d047f229a1..4142757080f8 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -22,6 +22,7 @@
*
*/
+#include <linux/nospec.h>
#include <sound/asound.h>
#define snd_kcontrol_chip(kcontrol) ((kcontrol)->private_data)
@@ -147,12 +148,14 @@ int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type);
static inline unsigned int snd_ctl_get_ioffnum(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
{
- return id->numid - kctl->id.numid;
+ unsigned int ioff = id->numid - kctl->id.numid;
+ return array_index_nospec(ioff, kctl->count);
}
static inline unsigned int snd_ctl_get_ioffidx(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)
{
- return id->index - kctl->id.index;
+ unsigned int ioff = id->index - kctl->id.index;
+ return array_index_nospec(ioff, kctl->count);
}
static inline unsigned int snd_ctl_get_ioff(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id)