media: ov9650: add a sanity check

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 <[email protected]> Signed-off-by: Mauro Carvalho Chehab <[email protected]>
laijs · Aug 26, 2019 · 093347a · 093347a
1 parent 31b8b0b
commit 093347a
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/drivers/media/i2c/ov9650.c b/drivers/media/i2c/ov9650.c
@@ -703,6 +703,11 @@ 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);