[Bug regex/29642] New: `regcomp` with multiple adjacent plus sign would exhaust memory quickly

[Bug regex/29642] New: `regcomp` with multiple adjacent plus sign would exhaust memory quickly

[linjy0410 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29642

            Bug ID: 29642
           Summary: `regcomp` with multiple adjacent plus sign would
                    exhaust memory quickly
           Product: glibc
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: regex
          Assignee: unassigned at sourceware dot org
          Reporter: linjy0410 at gmail dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

Hi! We found that in the latest pull, when `regcomp` with `REG_EXTENDED` is
compiling pattern with multiple adjacent '+', like
"1*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++",
the memory would be exhausted very quickly.
Because in `duplicate_tree` it exponentially calls `create_token_tree` which
malloc all the memory, looks like it's easy to cause serious DOS.
Checked the regex specification that said "multiple adjacent duplication
symbols ( '+', '*', '?', and intervals) produces undefined results.", and seems
like other regex implementation have handled this, maybe glibc needs to handle
it too?

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[Bug regex/29642] `regcomp` with multiple adjacent plus sign would exhaust memory quickly

[linjy0410 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29642

--- Comment #1 from jy l <linjy0410 at gmail dot com> ---
Created attachment 14373
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14373&action=edit
regex DOS poc

please be caution to run it since it might exhaust all the memory within few
seconds

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[Bug regex/29642] `regcomp` with multiple adjacent plus sign would exhaust memory quickly

[jwakely.gcc at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29642

Jonathan Wakely <jwakely.gcc at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jwakely.gcc at gmail dot com

--- Comment #2 from Jonathan Wakely <jwakely.gcc at gmail dot com> ---
Looks like a dup of PR 28864

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[Bug regex/29642] `regcomp` with multiple adjacent plus sign would exhaust memory quickly

[jwakely.gcc at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29642

--- Comment #3 from Jonathan Wakely <jwakely.gcc at gmail dot com> ---
Which seems to be a dup of PR 20095

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