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fpexif: Fix exif reader when pre-mature end-of-directory value is found in IFD. Issue #38904, patch by regs.

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git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@8044 8e941d3f-bd1b-0410-a28a-d453659cc2b4
This commit is contained in:
wp_xxyyzz
2021-05-22 22:06:21 +00:00
parent 22d20ee401
commit 9ac5119607
1 changed files with 12 additions and 3 deletions
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15
components/fpexif/fpeexifreadwrite.pas
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@@ -309,11 +309,13 @@ var
i: Integer; i: Integer;
ifdRec: TIFDRecord; ifdRec: TIFDRecord;
byteCount: Integer; byteCount: Integer;
data: TBytes; data: TBytes = nil;
n: Int64; n: Int64;
tagPos: Int64; tagPos: Int64;
newPos: Int64; newPos: Int64;
begin begin
ifdRec := Default(TIFDRecord);
// Read count of directory entries // Read count of directory entries
numRecords := FixEndian16(ReadWord(AStream)); numRecords := FixEndian16(ReadWord(AStream));
if (AParent = TAGPARENT_THUMBNAIL) and (numRecords > 10) then begin if (AParent = TAGPARENT_THUMBNAIL) and (numRecords > 10) then begin
@@ -326,7 +328,7 @@ begin
AStream.Position := tagPos; AStream.Position := tagPos;
// Read directory entry... // Read directory entry...
n := SizeOf(ifdRec); n := SizeOf(ifdRec);
if AStream.Read(ifdRec{%H-}, n) < n then begin if AStream.Read(ifdRec, n) < n then begin
Error(Format(rsReadIncompleteIFDRecord, [tagPos])); Error(Format(rsReadIncompleteIFDRecord, [tagPos]));
exit; exit;
end; end;
@@ -334,10 +336,17 @@ begin
if (ifdRec.TagID = 0) and (ifdRec.DataType = 0) and (ifdRec.DataCount = 0) and (ifdRec.DataValue = 0) then if (ifdRec.TagID = 0) and (ifdRec.DataType = 0) and (ifdRec.DataCount = 0) and (ifdRec.DataValue = 0) then
begin begin
// This is an empty IFD entry as found in images of the YUNEEC CGO3 camera // This is an empty IFD entry as found in images of the YUNEEC CGO3 camera
AStream.Position := AStream.Position + n; // see: https://www.lazarusforum.de/viewtopic.php?f=18&t=13356 and
// https://bugs.freepascal.org/view.php?id=38904
tagPos := tagPos + n;
Continue; Continue;
end; end;
if (ifdRec.TagID = 0) and (ifdRec.DataType = 0) then
// Unexpected end of directory (4 zero bytes), so breaking here.
// see: https://bugs.freepascal.org/view.php?id=38904
Break;
ifdRec.TagID := FixEndian16(ifdRec.TagID); ifdRec.TagID := FixEndian16(ifdRec.TagID);
ifdRec.DataType := FixEndian16(ifdRec.DataType); ifdRec.DataType := FixEndian16(ifdRec.DataType);
if not (ifdRec.DataType in [1..ord(High(TTagType))]) then begin if not (ifdRec.DataType in [1..ord(High(TTagType))]) then begin