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LibGfx: Add some validation to BMPLoader

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These changes fixed various asserts when I ran the fuzzer locally a
while ago.
This commit is contained in:
Nico Weber 2020-12-01 10:11:18 -05:00 committed by Andreas Kling
parent 1f86d88dc4
commit eef30bb05e
Notes: sideshowbarker 2024-07-19 01:07:41 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/eef30bb05e0
Pull-request: https://github.com/SerenityOS/serenity/pull/4292
1 changed files with 25 additions and 1 deletions
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26
Libraries/LibGfx/BMPLoader.cpp
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@ -798,6 +798,22 @@ static bool decode_bmp_dib(BMPLoadingContext& context)
error = true;
}
switch (context.dib.info.compression) {
case Compression::RGB:
case Compression::RLE8:
case Compression::RLE4:
case Compression::BITFIELDS:
case Compression::RLE24:
case Compression::PNG:
case Compression::ALPHABITFIELDS:
case Compression::CMYK:
case Compression::CMYKRLE8:
case Compression::CMYKRLE4:
break;
default:
error = true;
}
if (!error && !set_dib_bitmasks(context, streamer))
error = true;
@ -925,7 +941,7 @@ static bool uncompress_bmp_rle_data(BMPLoadingContext& context, ByteBuffer& buff
row++;
}
auto index = get_buffer_index();
if (index >= buffer.size()) {
if (index + 3 >= buffer.size()) {
IF_BMP_DEBUG(dbg() << "BMP has badly-formatted RLE data");
return false;
}
@ -1031,7 +1047,11 @@ static bool uncompress_bmp_rle_data(BMPLoadingContext& context, ByteBuffer& buff
if (byte == 1)
return true;
if (byte == 2) {
if (!streamer.has_u8())
return false;
u8 offset_x = streamer.read_u8();
if (!streamer.has_u8())
return false;
u8 offset_y = streamer.read_u8();
column += offset_x;
if (column >= total_columns) {
@ -1062,10 +1082,14 @@ static bool uncompress_bmp_rle_data(BMPLoadingContext& context, ByteBuffer& buff
// Optionally consume a padding byte
if (compression != Compression::RLE4) {
if (pixel_count % 2) {
if (!streamer.has_u8())
return false;
byte = streamer.read_u8();
}
} else {
if (((pixel_count + 1) / 2) % 2) {
if (!streamer.has_u8())
return false;
byte = streamer.read_u8();
}
}