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Handle malformed HEIC box types and invalid thumbnail offsets #253

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20 changes: 13 additions & 7 deletions exifread/core/exif_header.py
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Original file line number Diff line number Diff line change
Expand Up @@ -469,19 +469,25 @@ def extract_jpeg_thumbnail(self) -> None:
thumb_offset = self.tags.get("Thumbnail JPEGInterchangeFormat")
thumb_length = self.tags.get("Thumbnail JPEGInterchangeFormatLength")
if thumb_offset and thumb_length:
self.file_handle.seek(self.offset + thumb_offset.values[0])
size = thumb_length.values[0]
self.tags["JPEGThumbnail"] = self.file_handle.read(size)
try:
self.file_handle.seek(self.offset + thumb_offset.values[0])
size = thumb_length.values[0]
self.tags["JPEGThumbnail"] = self.file_handle.read(size)
except TypeError:
logger.debug("Invalid JPEG thumbnail offset or length, skipping")

# Sometimes in a TIFF file, a JPEG thumbnail is hidden in the MakerNote
# since it's not allowed in a uncompressed TIFF IFD
if "JPEGThumbnail" not in self.tags:
thumb_offset = self.tags.get("MakerNote JPEGThumbnail")
if thumb_offset:
self.file_handle.seek(self.offset + thumb_offset.values[0])
self.tags["JPEGThumbnail"] = self.file_handle.read(
thumb_offset.field_length
)
try:
self.file_handle.seek(self.offset + thumb_offset.values[0])
self.tags["JPEGThumbnail"] = self.file_handle.read(
thumb_offset.field_length
)
except TypeError:
logger.debug("Invalid MakerNote thumbnail offset, skipping")

def decode_maker_note(self) -> None:
"""
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8 changes: 7 additions & 1 deletion exifread/core/heic.py
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Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,13 @@ def get_string(self) -> bytes:
def next_box(self) -> Box:
pos = self.file_handle.tell()
size = self.get32()
kind = self.get(4).decode("ascii")
raw = self.get(4)
try:
kind = raw.decode("ascii")
except UnicodeDecodeError:
raise InvalidExif(
"Invalid HEIC box type at offset %d: %r" % (pos, raw)
)
box = Box(kind)
if size == 0:
# signifies 'to the end of the file', we shouldn't see this.
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