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Subject[PATCH 04/11] marvell-ccic: mcam-core: fix potential Spectre variant 1
fmt->index can be controlled by user-space, hence leading to a
potential exploitation of the Spectre variant 1 vulnerability.

Smatch warning:
drivers/media/platform/marvell-ccic/mcam-core.c:1323 mcam_vidioc_enum_fmt_vid_cap() warn: potential spectre issue 'mcam_formats'

Fix this by sanitizing fmt->index before using it to index
mcam_formats.

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
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/media/platform/marvell-ccic/mcam-core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/media/platform/marvell-ccic/mcam-core.c b/drivers/media/platform/marvell-ccic/mcam-core.c
index 80670ee..0a54dba 100644
--- a/drivers/media/platform/marvell-ccic/mcam-core.c
+++ b/drivers/media/platform/marvell-ccic/mcam-core.c
@@ -33,6 +33,8 @@

#include "mcam-core.h"

+#include <linux/nospec.h>
+
#ifdef MCAM_MODE_VMALLOC
/*
* Internal DMA buffer management. Since the controller cannot do S/G I/O,
@@ -1318,6 +1320,7 @@ static int mcam_vidioc_enum_fmt_vid_cap(struct file *filp,
{
if (fmt->index >= N_MCAM_FMTS)
return -EINVAL;
+ fmt->index = array_index_nospec(fmt->index, N_MCAM_FMTS);
strlcpy(fmt->description, mcam_formats[fmt->index].desc,
sizeof(fmt->description));
fmt->pixelformat = mcam_formats[fmt->index].pixelformat;
--
2.7.4
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