[alsa-devel] [PATCH 6/8] ALSA: asihpi: Hardening for potential Spectre v1

[Takashi Iwai]

As the recent Smatch warned, 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=2
Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/pci/asihpi/hpimsginit.c | 13 +++++++++----
 sound/pci/asihpi/hpioctl.c    |  4 +++-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/sound/pci/asihpi/hpimsginit.c b/sound/pci/asihpi/hpimsginit.c
index 7eb617175fde..a31a70dccecf 100644
--- a/sound/pci/asihpi/hpimsginit.c
+++ b/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;
diff --git a/sound/pci/asihpi/hpioctl.c b/sound/pci/asihpi/hpioctl.c
index 5badd08e1d69..b1a2a7ea4172 100644
--- a/sound/pci/asihpi/hpioctl.c
+++ b/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");
@@ -186,7 +187,8 @@ 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,
-- 
2.16.3