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NVDA PDF Actual Text bug #7034

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Wildted opened this Issue Mar 30, 2017 · 1 comment

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@Wildted

Wildted commented Mar 30, 2017

There is currently a serious bug in NVDA as follows. If you add some Actual Text to a PDF tag and then delete the actual text again, an empty Actual Text attribute will be created in the PDF. This will cause NVDA to stop working completely (remain completely silent) on a Windows 7 machine. On a Windows 8 or Windows 10 machine, Acrobat or Adobe Reader will crash 100% of the time if you try to open such a file with NVDA running. This bug dos not affect JAWS, ZoomText, SuperNova, MAGic, Read&Write Gold or Claro Read.

The attached file that includes the word "Edit" is so affected (will crash). I also attach a version ("Original") which works fine.

For info I have experienced this bug in perhaps 50 different PDFs before I worked out what was going on (not just the attached files).

Thanks

Coram Life Education Bro 2015 - Edit.pdf
Coram Life Education Bro 2015 - Original.pdf

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jcsteh Mar 31, 2017

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The crash is the same as the first crash in #7021.

Technical: Getting the IPDDomNode for one of the nodes in this document
fails with E_FAIL for some reason and returns null. The crash is
because NVDA doesn't check for this and tries to dereference it. It
probably shouldn't be failing anyway, but that doesn't excuse the lack of a
check.

In this case, adding that check does fix the crash.

Contributor

jcsteh commented Mar 31, 2017

The crash is the same as the first crash in #7021.

Technical: Getting the IPDDomNode for one of the nodes in this document
fails with E_FAIL for some reason and returns null. The crash is
because NVDA doesn't check for this and tries to dereference it. It
probably shouldn't be failing anyway, but that doesn't excuse the lack of a
check.

In this case, adding that check does fix the crash.

@jcsteh jcsteh self-assigned this Mar 31, 2017

jcsteh added a commit that referenced this issue Apr 4, 2017

@jcsteh jcsteh closed this in #7035 May 2, 2017

@nvaccessAuto nvaccessAuto added this to the 2017.2 milestone May 2, 2017

jcsteh added a commit that referenced this issue May 2, 2017

Adobe Acrobat Reader no longer crashes in certain PDF documents (spec…
…ifically, those containing empty ActualText attributes). (PR #7035; issues #7021, #7034)

* Adobe Acrobat Reader no longer crashes in certain PDF documents (specifically, those containing empty ActualText attributes).

adobeAcrobat vbuf backend: get_PDDomNode can fail and return null, so check for a null pointer before trying to use it.

* Address review comments.
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