linux-kernel - Re: [PATCH v7 2/4] x86/stackvalidate: Compile-time stack validation

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Message-ID: <20150721120453.GA11122@treble.redhat.com>
Date:	Tue, 21 Jul 2015 07:04:53 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Namhyung Kim <namhyung@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Pedro Alves <palves@...hat.com>, x86@...nel.org,
	live-patching@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 2/4] x86/stackvalidate: Compile-time stack validation

On Tue, Jul 21, 2015 at 10:02:03AM +0200, Ingo Molnar wrote:
> 
> * Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> 
> > > > +int main(int argc, char *argv[])
> > > > +{
> > > > +       struct elf *elf;
> > > > +       int ret = 0, warnings = 0;
> > > > +
> > > > +       argp_parse(&argp, argc, argv, 0, 0, &args);
> > > > +
> > > > +       elf = elf_open(args.args[0]);
> > > > +       if (!elf) {
> > > > +               fprintf(stderr, "error reading elf file %s\n", args.args[0]);
> > > > +               return 1;
> > > > +       }
> > > > +
> > > > +       ret = decode_sections(elf);
> > > > +       if (ret < 0)
> > > > +               goto out;
> > > > +       warnings += ret;
> > > > +
> > > > +       ret = validate_functions(elf);
> > > > +       if (ret < 0)
> > > > +               goto out;
> > > > +       warnings += ret;
> > > > +
> > > > +       ret = validate_uncallable_instructions(elf);
> > > > +       if (ret < 0)
> > > > +               goto out;
> > > > +       warnings += ret;
> > > > +
> > > > +out:
> > > 
> > > elf_close(elf);  ??
> > 
> > I intentionally left out the call to elf_close() here, since this is the
> > exit path and the kernel will free the memory anyway.
> 
> OTOH it makes Valgrind runs harder to interpret, as real leaks won't be visible.
> 
> So I'd only do intentional leaks only if it's truly, measurably improves 
> performance.

Ok.  I'll fix the leaks.

-- 
Josh
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