[PATCH AUTOSEL 6.2 12/37] media: imx-jpeg: Bounds check sizeimage access

Sasha Levin
2023-05-01T03:07:32Z

From: Kees Cook <keescook@chromium.org>

[ Upstream commit 474acc639fc8671fa4c1919d9e03253c82b6d321 ]

The call of mxc_jpeg_get_plane_size() from mxc_jpeg_dec_irq() sets
plane_no argument to 1. The compiler sees that it's possible to end up
with an access beyond the bounds of sizeimage, if mem_planes was too
large:

if (plane_no >= fmt->mem_planes) // mem_planes = 2+
return 0;

if (fmt->mem_planes == fmt->comp_planes) // comp_planes != mem_planes
return q_data->sizeimage[plane_no];

if (plane_no < fmt->mem_planes - 1) // mem_planes = 2
return q_data->sizeimage[plane_no];

comp_planes == 0 or 1 is safe. comp_planes > 2 would be out of bounds.

(This isn't currently possible given the contents of mxc_formats, though.)

Silence the warning by bounds checking comp_planes for future
robustness. Seen with GCC 13:

In function 'mxc_jpeg_get_plane_size',
inlined from 'mxc_jpeg_dec_irq' at ../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c:729:14:
../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c:641:42: warning: array subscript 2 is above array bounds of 'u32[2]' {aka 'unsigned int[2]'} [-Warray-bounds=]
641 | size += q_data->sizeimage[i];
| ~~~~~~~~~~~~~~~~~^~~
In file included from ../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg-hw.h:112,
from ../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c:63:
../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h: In function 'mxc_jpeg_dec_irq':
../drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.h:84:41: note: while referencing 'sizeimage'
84 | u32 sizeimage[MXC_JPEG_MAX_PLANES];
| ^~~~~~~~~

Cc: Mirela Rabulea <mirela.rabulea@nxp.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
index f085f14d676ad..c898116b763a2 100644
--- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
+++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
@@ -637,6 +637,11 @@ static u32 mxc_jpeg_get_plane_size(struct mxc_jpeg_q_data *q_data, u32 plane_no)
return q_data->sizeimage[plane_no];

size = q_data->sizeimage[fmt->mem_planes - 1];
+
+ /* Should be impossible given mxc_formats. */
+ if (WARN_ON_ONCE(fmt->comp_planes > ARRAY_SIZE(q_data->sizeimage)))
+ return size;
+
for (i = fmt->mem_planes; i < fmt->comp_planes; i++)
size += q_data->sizeimage[i];

--
2.39.2