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LibGfx: Validate bit depths, and don't assert on invalid color type

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The PNG spec says that each color type only allows certain bit depths,
so add explicit checks for that.
This commit is contained in:
Nico Weber 2020-11-29 14:37:15 -05:00 • committed by Andreas Kling
parent fe999d6281
commit 34c5478f31
1 changed files with 11 additions and 1 deletions
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12
Libraries/LibGfx/PNGLoader.cpp
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@ -847,22 +847,32 @@ static bool process_IHDR(const ByteBuffer& data, PNGLoadingContext& context)
switch (context.color_type) {
case 0: // Each pixel is a grayscale sample.
if (context.bit_depth != 1 && context.bit_depth != 2 && context.bit_depth != 4 && context.bit_depth != 8 && context.bit_depth != 16)
return false;
context.channels = 1;
break;
case 4: // Each pixel is a grayscale sample, followed by an alpha sample.
if (context.bit_depth != 8 && context.bit_depth != 16)
return false;
context.channels = 2;
break;
case 2: // Each pixel is an RGB sample
if (context.bit_depth != 8 && context.bit_depth != 16)
return false;
context.channels = 3;
break;
case 3: // Each pixel is a palette index; a PLTE chunk must appear.
if (context.bit_depth != 1 && context.bit_depth != 2 && context.bit_depth != 4 && context.bit_depth != 8)
return false;
context.channels = 1;
break;
case 6: // Each pixel is an RGB sample, followed by an alpha sample.
if (context.bit_depth != 8 && context.bit_depth != 16)
return false;
context.channels = 4;
break;
default:
ASSERT_NOT_REACHED();
return false;
}
return true;
}