ALSA: asihpi: Hardening for potential Spectre v1

As recently Smatch suggested, a couple of places in ASIHPI driver may
expand the array directly from the user-space value with speculation:
  sound/pci/asihpi/hpimsginit.c:70 hpi_init_response() warn: potential spectre issue 'res_size' (local cap)
  sound/pci/asihpi/hpioctl.c:189 asihpi_hpi_ioctl() warn: potential spectre issue 'adapters'

This patch puts array_index_nospec() for hardening against them.

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

CVE-2017-5753

(cherry picked from commit f9d94b57)
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

sound/pci/asihpi/hpimsginit.c

@@ -23,6 +23,7 @@
 
 #include "hpi_internal.h"
 #include "hpimsginit.h"
+#include <linux/nospec.h>
 
 /* The actual message size for each object type */
 static u16 msg_size[HPI_OBJ_MAXINDEX + 1] = HPI_MESSAGE_SIZE_BY_OBJECT;
@@ -39,10 +40,12 @@ static void hpi_init_message(struct hpi_message *phm, u16 object,
 {
 	u16 size;
 
-	if ((object > 0) && (object <= HPI_OBJ_MAXINDEX))
+	if ((object > 0) && (object <= HPI_OBJ_MAXINDEX)) {
+		object = array_index_nospec(object, HPI_OBJ_MAXINDEX + 1);
 		size = msg_size[object];
-	else
+	} else {
 		size = sizeof(*phm);
+	}
 
 	memset(phm, 0, size);
 	phm->size = size;
@@ -66,10 +69,12 @@ void hpi_init_response(struct hpi_response *phr, u16 object, u16 function,
 {
 	u16 size;
 
-	if ((object > 0) && (object <= HPI_OBJ_MAXINDEX))
+	if ((object > 0) && (object <= HPI_OBJ_MAXINDEX)) {
+		object = array_index_nospec(object, HPI_OBJ_MAXINDEX + 1);
 		size = res_size[object];
-	else
+	} else {
 		size = sizeof(*phr);
+	}
 
 	memset(phr, 0, sizeof(*phr));
 	phr->size = size;

sound/pci/asihpi/hpioctl.c

@@ -33,6 +33,7 @@
 #include <linux/stringify.h>
 #include <linux/module.h>
 #include <linux/vmalloc.h>
+#include <linux/nospec.h>
 
 #ifdef MODULE_FIRMWARE
 MODULE_FIRMWARE("asihpi/dsp5000.bin");
@@ -182,7 +183,8 @@ long asihpi_hpi_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		struct hpi_adapter *pa = NULL;
 
 		if (hm->h.adapter_index < ARRAY_SIZE(adapters))
-			pa = &adapters[hm->h.adapter_index];
+			pa = &adapters[array_index_nospec(hm->h.adapter_index,
+							  ARRAY_SIZE(adapters))];
 
 		if (!pa || !pa->adapter || !pa->adapter->type) {
 			hpi_init_response(&hr->r0, hm->h.object,