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Treat Exif.Sony1.PreviewImage as undefined tag (backport #2015) #2016

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Dec 14, 2021
Merged

Treat Exif.Sony1.PreviewImage as undefined tag (backport #2015) #2016

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30 changes: 14 additions & 16 deletions src/tiffvisitor_int.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1568,7 +1568,6 @@ namespace Exiv2 {
return;
}
p += 4;
uint32_t isize= 0; // size of Exif.Sony1.PreviewImage

if (count > std::numeric_limits<uint32_t>::max() / typeSize) {
throw Error(kerArithmeticOverflow);
Expand All @@ -1581,7 +1580,19 @@ namespace Exiv2 {
|| static_cast<int32_t>(baseOffset()) + offset <= 0)) {
// #1143
if ( object->tag() == 0x2001 && std::string(groupName(object->group())) == "Sony1" ) {
isize=size;
// This tag is Exif.Sony1.PreviewImage, which refers to a preview image which is
// not stored in the metadata. Instead it is stored at the end of the file, after
// the main image. The value of `size` refers to the size of the preview image, not
// the size of the tag's payload, so we set it to zero here so that we don't attempt
// to read those bytes from the metadata. We currently leave this tag as "undefined",
// although we may attempt to handle it better in the future. More discussion of
// this issue can be found here:
//
// https://github.com/Exiv2/exiv2/issues/2001
// https://github.com/Exiv2/exiv2/pull/2008
// https://github.com/Exiv2/exiv2/pull/2013
typeId = undefined;
size = 0;
} else {
#ifndef SUPPRESS_WARNINGS
EXV_ERROR << "Offset of directory " << groupName(object->group())
Expand Down Expand Up @@ -1629,20 +1640,7 @@ namespace Exiv2 {
}
Value::AutoPtr v = Value::create(typeId);
enforce(v.get() != NULL, kerCorruptedMetadata);
if ( !isize ) {
v->read(pData, size, byteOrder());
} else {
// Prevent large memory allocations: https://github.com/Exiv2/exiv2/issues/1881
enforce(isize <= 1024 * 1024, kerCorruptedMetadata);

// #1143 Write a "hollow" buffer for the preview image
// Sadly: we don't know the exact location of the image in the source (it's near offset)
// And neither TiffReader nor TiffEntryBase have access to the BasicIo object being processed
byte* buffer = (byte*) ::malloc(isize);
::memset(buffer,0,isize);
v->read(buffer,isize, byteOrder());
::free(buffer);
}
v->read(pData, size, byteOrder());

object->setValue(v);
object->setData(pData, size);
Expand Down
8 changes: 2 additions & 6 deletions tests/bugfixes/github/test_issue_1881.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,9 +14,5 @@ class SonyPreviewImageLargeAllocation(metaclass=CaseMeta):
filename2 = path("$tmp_path/issue_1881_coverage.jpg")
commands = ["$exiv2 -q -d I rm $filename1", "$exiv2 -q -d I rm $filename2"]
stdout = ["",""]
stderr = [
"""Exiv2 exception in erase action for file $filename1:
$kerCorruptedMetadata
""",
""]
retval = [1,0]
stderr = ["",""]
retval = [0,0]