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Re: [PATCH v2 01/10] argp-parse.c (__argp_input): Don't crash if pstate

From: Colin Watson
Subject: Re: [PATCH v2 01/10] argp-parse.c (__argp_input): Don't crash if pstate is NULL
Date: Tue, 7 Dec 2021 17:37:24 +0000

On Tue, Dec 07, 2021 at 11:59:01AM -0500, Robbie Harwood wrote:
> Bruno Haible <bruno@clisp.org> writes:
> > I don't think this patch is needed, because:
> >
> > 1) The application cannot construct a 'struct argp_state' by itself, since 
> > [1]
> >    says that the 'struct argp_state' contains a member 'pstate' that is
> >    "Private, for use by the argp implementation.".
> >
> > 2) The only place in the gnulib / glibc code where a 'struct argp_state' is
> >    being constructed, is in function parser_init, invoked from 'argp_parse',
> >    and there a non-NULL value is assigned.
> >
> > In other words, there is no way, compliant with the documented API, that a
> > NULL pointer can arise as state->pstate.
> >
> > Bruno
> >
> > [1] 
> > https://www.gnu.org/software/libc/manual/html_node/Argp-Parsing-State.html
> Thanks for taking a look.  I don't have more information on this one
> beyond the little that's in the commit, so unless Colin remembers why
> this was needed in 2011, I'll propose grub drop it at some point.

The original problem was:


At the time, __argp_help looked like this:

  void __argp_help (const struct argp *argp, FILE *stream,
                    unsigned flags, char *name)
    struct argp_state state;
    memset (&state, 0, sizeof state);
    state.root_argp = argp;
    _help (argp, &state, stream, flags, name);

As a result it was possible at the time to encounter the case where
state was non-NULL but state->pstate was NULL.  However, this seems to
have been fixed differently some time ago:


So I think it's probably fine to drop this patch from GRUB.

Colin Watson (he/him)                              [cjwatson@ubuntu.com]

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