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fix jdimension overflow in jpegli_crop_scanline bounds check #242

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fix jdimension overflow in jpegli_crop_scanline bounds check #242

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3 changes: 2 additions & 1 deletion lib/jpegli/decode.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -939,7 +939,8 @@ void jpegli_crop_scanline(j_decompress_ptr cinfo, JDIMENSION* xoffset,
JPEGLI_ERROR("Output cropping is not supported in raw data mode");
}
if (xoffset == nullptr || width == nullptr || *width == 0 ||
*xoffset + *width > cinfo->output_width) {
*xoffset >= cinfo->output_width ||
*width > cinfo->output_width - *xoffset) {
JPEGLI_ERROR("jpegli_crop_scanline: Invalid arguments");
}
// TODO(szabadka) Skip the IDCT for skipped over blocks.
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19 changes: 19 additions & 0 deletions lib/jpegli/error_handling_test.cc
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Expand Up @@ -1140,6 +1140,25 @@ TEST(DecoderErrorHandlingTest, NoReadScanlines) {
jpegli_destroy_decompress(&cinfo);
}

TEST(DecoderErrorHandlingTest, CropScanlineArgumentOverflow) {
jpeg_decompress_struct cinfo = {};
const auto try_catch_block = [&]() -> bool {
ERROR_HANDLER_SETUP(jpegli);
jpegli_create_decompress(&cinfo);
jpegli_mem_src(&cinfo, kCompressed0, kLen0);
jpegli_read_header(&cinfo, TRUE);
jpegli_start_decompress(&cinfo);
// xoffset + width wraps around JDIMENSION and lands below output_width, so
// an unguarded sum accepts this out-of-range crop window.
JDIMENSION xoffset = 0xffffffffu;
JDIMENSION width = 2;
jpegli_crop_scanline(&cinfo, &xoffset, &width);
return true;
};
EXPECT_FALSE(try_catch_block());
jpegli_destroy_decompress(&cinfo);
}

const size_t kMaxImageWidth = 0xffff;
JSAMPLE kOutputBuffer[MAX_COMPONENTS * kMaxImageWidth];

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