From: Maciej Matraszek <m.matraszek@samsung.com>
To: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
Mauro Carvalho Chehab <m.chehab@samsung.com>,
Hans Verkuil <hans.verkuil@cisco.com>,
Lars-Peter Clausen <lars@metafoo.de>,
Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Maciej Matraszek <m.matraszek@samsung.com>,
stable@vger.kernel.org
Subject: [PATCH v3] [media] v4l2-common: fix overflow in v4l_bound_align_image()
Date: Mon, 15 Sep 2014 10:14:48 +0200 [thread overview]
Message-ID: <1410768888-14367-1-git-send-email-m.matraszek@samsung.com> (raw)
Fix clamp_align() used in v4l_bound_align_image() to prevent overflow when
passed large value like UINT32_MAX. In the current implementation:
clamp_align(UINT32_MAX, 8, 8192, 3)
returns 8, because in line:
x = (x + (1 << (align - 1))) & mask;
x overflows to (-1 + 4) & 0x7 = 3, while expected value is 8192.
v4l_bound_align_image() is heavily used in VIDIOC_S_FMT
and VIDIOC_SUBDEV_S_FMT ioctls handlers, and documentation of the latter
explicitly states that:
"The modified format should be as close as possible to the original request."
-- http://linuxtv.org/downloads/v4l-dvb-apis/vidioc-subdev-g-fmt.html
Thus one would expect, that passing UINT32_MAX as format width and height
will result in setting maximum possible resolution for the device.
Particularly, when the driver doesn't support VIDIOC_ENUM_FRAMESIZES ioctl,
which is common in the codebase.
Fixes: b0d3159be9a3 ("V4L/DVB (11901): v4l2: Create helper function for bounding and aligning images")
Signed-off-by: Maciej Matraszek <m.matraszek@samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: <stable@vger.kernel.org>
---
v2: use clamp() instead of clamp_t(), as suggested by Sakari
v3: correct way of submitting patches for inclusion in the stable tree
drivers/media/v4l2-core/v4l2-common.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
index ccaa38f65cf1..2e9d81f4c1a5 100644
--- a/drivers/media/v4l2-core/v4l2-common.c
+++ b/drivers/media/v4l2-core/v4l2-common.c
@@ -435,16 +435,13 @@ static unsigned int clamp_align(unsigned int x, unsigned int min,
/* Bits that must be zero to be aligned */
unsigned int mask = ~((1 << align) - 1);
+ /* Clamp to aligned min and max */
+ x = clamp(x, (min + ~mask) & mask, max & mask);
+
/* Round to nearest aligned value */
if (align)
x = (x + (1 << (align - 1))) & mask;
- /* Clamp to aligned value of min and max */
- if (x < min)
- x = (min + ~mask) & mask;
- else if (x > max)
- x = max & mask;
-
return x;
}
--
1.9.1
reply other threads:[~2014-09-15 8:16 UTC|newest]
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