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media: ov9650: add a sanity check

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[ Upstream commit 093347abc7a4e0490e3c962ecbde2dc272a8f708 ]

As pointed by cppcheck:

	[drivers/media/i2c/ov9650.c:706]: (error) Shifting by a negative value is undefined behaviour
	[drivers/media/i2c/ov9650.c:707]: (error) Shifting by a negative value is undefined behaviour
	[drivers/media/i2c/ov9650.c:721]: (error) Shifting by a negative value is undefined behaviour

Prevent mangling with gains with invalid values.

As pointed by Sylvester, this should never happen in practice,
as min value of V4L2_CID_GAIN control is 16 (gain is always >= 16
and m is always >= 0), but it is too hard for a static analyzer
to get this, as the logic with validates control min/max is
elsewhere inside V4L2 core.

Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab 2019-08-22 11:55:07 -03:00 • committed by Greg Kroah-Hartman
parent 9dfd33530c
commit 7ff7d1e7a7
1 changed files with 5 additions and 0 deletions
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5
drivers/media/i2c/ov9650.c
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@ -707,6 +707,11 @@ static int ov965x_set_gain(struct ov965x *ov965x, int auto_gain)
for (m = 6; m >= 0; m--)
if (gain >= (1 << m) * 16)
break;
/* Sanity check: don't adjust the gain with a negative value */
if (m < 0)
return -EINVAL;
rgain = (gain - ((1 << m) * 16)) / (1 << m);
rgain |= (((1 << m) - 1) << 4);