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[Éric Piel (Delmic) <piel@xxxxxxxxxx>]

Public bug reported:

The patch debian/patches/CVE-2014-8128-5.patch appears to break saving TIFF files with compression predictor.
It seems the data is correctly saved, but the "predictor" tag is not, which prevents reading the data correctly again.

This happens both on precise (release 3.9.5-2ubuntu1.7) and on trusty
(release 4.0.3-7ubuntu0.2).

I'm attaching an example TIFF file "small.tiff" for showing the
behaviour. It is compressed in LZW without predictor, so it is
written/read correctly.

However, if you recompress it with this command, the error happens:
$ tiffcp -c lzw:2 small.tiff small-c2.tiff

Then displaying it in eog shows a completely different image. Tiffinfo indicates a problem with the tags:
$ tiffinfo small-c2-bad.tiff | grep Predictor
TIFFReadDirectory: Warning, small-c2-bad.tiff: unknown field with tag 8224 (0x2020) encountered.

Comparing it with a good version of the file (generated with a previous version of libtiff):
$ tiffinfo small-c2-good.tiff | grep Predictor
  Predictor: horizontal differencing 2 (0x2)

$ tiffcmp small-c2.tiff small-c2-good.tiff 
TIFFReadDirectory: Warning, small-c2-bad.tiff: unknown field with tag 8224 (0x2020) encountered.
Predictor tag appears only in small-c2-good.tiff

** Affects: tiff (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "Example TIFF file without predictor"
   https://bugs.launchpad.net/bugs/1439186/+attachment/4362958/+files/small.tiff

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https://bugs.launchpad.net/bugs/1439186

Title:
  [REGRESSION] Predictor tag fails to be written correctly

Status in tiff package in Ubuntu:
  New

Bug description:
  The patch debian/patches/CVE-2014-8128-5.patch appears to break saving TIFF files with compression predictor.
  It seems the data is correctly saved, but the "predictor" tag is not, which prevents reading the data correctly again.

  This happens both on precise (release 3.9.5-2ubuntu1.7) and on trusty
  (release 4.0.3-7ubuntu0.2).

  I'm attaching an example TIFF file "small.tiff" for showing the
  behaviour. It is compressed in LZW without predictor, so it is
  written/read correctly.

  However, if you recompress it with this command, the error happens:
  $ tiffcp -c lzw:2 small.tiff small-c2.tiff

  Then displaying it in eog shows a completely different image. Tiffinfo indicates a problem with the tags:
  $ tiffinfo small-c2-bad.tiff | grep Predictor
  TIFFReadDirectory: Warning, small-c2-bad.tiff: unknown field with tag 8224 (0x2020) encountered.

  Comparing it with a good version of the file (generated with a previous version of libtiff):
  $ tiffinfo small-c2-good.tiff | grep Predictor
    Predictor: horizontal differencing 2 (0x2)

  $ tiffcmp small-c2.tiff small-c2-good.tiff 
  TIFFReadDirectory: Warning, small-c2-bad.tiff: unknown field with tag 8224 (0x2020) encountered.
  Predictor tag appears only in small-c2-good.tiff

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