Re: [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data

> On Tue, Sep 06, 2016 at 04:06:32PM +0200, Johannes Schindelin wrote:
> 
> > > I think re_search() the correct replacement function but it's been a
> > > while since I've looked into it.
> > 
> > The segfault I investigated happened in a call to strlen(). I see many
> > calls to strlen() in compat/regex/... The one that triggers the segfault
> > is in regexec(), compat/regex/regexec.c:241.
> 
> Yes, that is the important one, I think. The others are for patterns,
> error msgs, etc. Of course strlen() is not the only function that cares
> about NUL delimiters (and there might even be a "while (*p)" somewhere
> in the code).
> 
> I always assumed the _point_ of re_search taking a ptr/len pair was
> exactly to handle this case. The documentation[1] says:
> 
>    `string` is the string you want to match; it can contain newline and
>    null characters. `size` is the length of that string.
> 
> Which seems pretty definitive to me (that's for re_match(), but
> re_search() is defined in the docs in terms of re_match()).

> > The bigger problem is that re_search() is defined in the __USE_GNU section
> > of regex.h, and I do not think it is appropriate to universally #define
> > said constant before #include'ing regex.h. So it would appear that major
> > surgery would be required if we wanted to use regular expressions on
> > strings that are not NUL-terminated.
> 
> We can contain this to the existing compat/regexec/regexec.c, and just
> provide a wrapper that is similar to regexec but takes a ptr/len pair.