From 0e714d27786ce1fb3efa9aac58abc096e68b1c2a Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 17 Jul 2018 12:39:00 -0500
Subject: [PATCH] vfio/pci: Fix potential Spectre v1
Git-commit: 0e714d27786ce1fb3efa9aac58abc096e68b1c2a
Patch-mainline: v4.18-rc6
References: bsc#1051510
info.index can be indirectly controlled by user-space, hence leading
to a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/vfio/pci/vfio_pci.c:734 vfio_pci_ioctl()
Warn: potential spectre issue 'vdev->region'
Fix this by sanitizing info.index before indirectly using it to index
vdev->region
Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].
[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2
Cc: stable@vger.kernel.org
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/vfio/pci/vfio_pci.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index b423a309a6e0..125b58eff936 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -28,6 +28,7 @@
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/vgaarb.h>
+#include <linux/nospec.h>
#include "vfio_pci_private.h"
@@ -727,6 +728,9 @@ static long vfio_pci_ioctl(void *device_data,
if (info.index >=
VFIO_PCI_NUM_REGIONS + vdev->num_regions)
return -EINVAL;
+ info.index = array_index_nospec(info.index,
+ VFIO_PCI_NUM_REGIONS +
+ vdev->num_regions);
i = info.index - VFIO_PCI_NUM_REGIONS;
--
2.18.0