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@xxxxxxxxxxx>
Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
v2: use clamp() instead of clamp_t(), as suggested by Sakari
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
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