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Re: Commit: Use of alloca considered dangerous
- From: <Paul_Koning at Dell dot com>
- To: <nickc at redhat dot com>
- Cc: <binutils at sourceware dot org>
- Date: Mon, 21 Mar 2016 16:56:01 +0000
- Subject: Re: Commit: Use of alloca considered dangerous
- Authentication-results: sourceware.org; auth=none
- References: <87mvprx079 dot fsf at redhat dot com>
> On Mar 21, 2016, at 12:30 PM, Nick Clifton <email@example.com> wrote:
> Hi Guys,
> It was pointed out to me the other day that there are some unbounded
> calls to alloca in the binutils, which in theory could lead to
> exploits. So I tried adding -Wstack-usage=NNN to the command line and
> discovered that gcc would complain about any use of alloca, even
> bounded ones. Still they were easy to fix, and removing the use of
> alloca, and variable length local arrays as well, seems like a good
I agree that alloca() needs bounds checks, but I don't see why you say that avoiding alloca entirely is "a good idea".
> So I am applying the attached patch. It enables -Wstack-usage when
> -Werror is in effect.
The documented meaning of -Werror is that it turns all (currently enabled) warnings into errors, nothing more. For it to have a side effect of enabling some not previously enabled warning is not a good idea.