kc3-lang/libxml2

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    Commit

  • Hash : dcb80b92
    Author : Nick Wellnhofer
    Date : 2021-02-20T20:30:43 

    Fix slow parsing of HTML with encoding errors

Under certain circumstances, the HTML parser would try to guess and
switch input encodings multiple times, leading to slow processing of
documents with encoding errors. The repeated scanning of the input
buffer when guessing encodings could even lead to quadratic behavior.

The code htmlCurrentChar probably assumed that if there's an encoding
handler, it is guaranteed to produce valid UTF-8. This holds true in
general, but if the detected encoding was "UTF-8", the UTF8ToUTF8
encoding handler simply invoked memcpy without checking for invalid
UTF-8. This still must be fixed, preferably by not using this handler
at all.

Also leave a note that switching encodings twice seems impossible to
implement correctly. Add a check when handling UTF-8 encoding errors
in htmlCurrentChar to avoid this situation, even if encoders produce
invalid UTF-8.

Found by OSS-Fuzz.

  • README

  •                   XML toolkit from the GNOME project

Full documentation is available on-line at
    http://xmlsoft.org/

This code is released under the MIT Licence see the Copyright file.

To build on an Unixised setup:
   ./configure ; make ; make install
   if the ./configure file does not exist, run ./autogen.sh instead.
To build on Windows:
   see instructions on win32/Readme.txt

To assert build quality:
   on an Unixised setup:
      run make tests
   otherwise:
       There is 3 standalone tools runtest.c runsuite.c testapi.c, which
       should compile as part of the build or as any application would.
       Launch them from this directory to get results, runtest checks 
       the proper functioning of libxml2 main APIs while testapi does
       a full coverage check. Report failures to the list.

To report bugs, follow the instructions at: 
  http://xmlsoft.org/bugs.html

A mailing-list xml@gnome.org is available, to subscribe:
    http://mail.gnome.org/mailman/listinfo/xml

The list archive is at:
    http://mail.gnome.org/archives/xml/

All technical answers asked privately will be automatically answered on
the list and archived for public access unless privacy is explicitly
required and justified.

Daniel Veillard

$Id$

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