From: Alan Modra <amodra@gmail.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: binutils@sourceware.org
Subject: Re: Recursion in as_info_where
Date: Mon, 6 Feb 2023 12:11:22 +1030 [thread overview]
Message-ID: <Y+Bawj1NBn0qsP9c@squeak.grove.modra.org> (raw)
In-Reply-To: <c39ae5e6-a8e2-26e5-f312-e7c052820cb5@suse.com>
On Fri, Feb 03, 2023 at 02:44:06PM +0100, Jan Beulich wrote:
> On 01.02.2023 12:59, Alan Modra wrote:
> > On Wed, Feb 01, 2023 at 10:24:25AM +0100, Jan Beulich wrote:
> >> On 01.02.2023 07:36, Alan Modra via Binutils wrote:
> >>> This function has a gas_assert, ie. possible call to as_abort, which
> >>> calls as_report_context, which calls as_info_where. Attached fuzzer
> >>> testcase managed to trigger a stack overflow.
> >>>
> >>> * messages.c (as_info_where): Don't gas_assert.
> >>>
> >>> diff --git a/gas/messages.c b/gas/messages.c
> >>> index 0db075d779c..7c018acf69f 100644
> >>> --- a/gas/messages.c
> >>> +++ b/gas/messages.c
> >>> @@ -141,8 +141,6 @@ as_info_where (const char *file, unsigned int line, unsigned int indent,
> >>> va_list args;
> >>> char buffer[2000];
> >>>
> >>> - gas_assert (file != NULL && line > 0 && indent <= INT_MAX);
> >>
> >> If this go in the way, isn't it that the assertion actually triggered?
> >> In which case shouldn't the cause for it triggering be addressed
> >> instead, to avoid subsequent knock-on damage (e.g. from de-referencing
> >> "file"? (I may want to play with the testcase a little myself.)
> >
> > The testcase is really weird, something that no programmer would ever
> > write. It failed the assert with line == 0. I'll let you discover
> > the horrible "# line file" with embedded \0 that gets you there. :-)
>
> Sure. That's an interaction bug between read_a_source_file()'s bumping
> of line numbers and s_linefile() trying to compensate. I have a fix for
> that, but I'll want to give it wider testing before posting.
>
> As to the assertion here, I'd prefer if we would keep it, and do e.g.
> the below instead. Thoughts?
I think it is bad practice for a low-level error handling function to
assert.
--
Alan Modra
Australia Development Lab, IBM
prev parent reply other threads:[~2023-02-06 1:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-01 6:36 Alan Modra
2023-02-01 9:24 ` Jan Beulich
2023-02-01 11:59 ` Alan Modra
2023-02-03 13:44 ` Jan Beulich
2023-02-06 1:41 ` Alan Modra [this message]
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