linux-kernel - Re: [PATCH v12 02/14] unwind_user: Add frame pointer support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250630225603.72c84e67@gandalf.local.home>
Date: Mon, 30 Jun 2025 22:56:03 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 bpf@...r.kernel.org, x86@...nel.org, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>, Peter Zijlstra
 <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, Jiri Olsa
 <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>, Thomas Gleixner
 <tglx@...utronix.de>, Andrii Nakryiko <andrii@...nel.org>, Indu Bhagat
 <indu.bhagat@...cle.com>, "Jose E. Marchesi" <jemarch@....org>, Beau
 Belgrave <beaub@...ux.microsoft.com>, Jens Remus <jremus@...ux.ibm.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Jens Axboe <axboe@...nel.dk>,
 Florian Weimer <fweimer@...hat.com>
Subject: Re: [PATCH v12 02/14] unwind_user: Add frame pointer support

On Mon, 30 Jun 2025 19:10:09 -0700
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Mon, 30 Jun 2025 at 17:54, Steven Rostedt <rostedt@...dmis.org> wrote:
> >
> > +       /* stack going in wrong direction? */
> > +       if (cfa <= state->sp)
> > +               goto done;  
> 
> I suspect this should do a lot more testing.

Sure.

> 
> > +       /* Find the Return Address (RA) */
> > +       if (get_user(ra, (unsigned long *)(cfa + frame->ra_off)))
> > +               goto done;
> > +
> > +       if (frame->fp_off && get_user(fp, (unsigned long __user *)(cfa + frame->fp_off)))
> > +               goto done;  
> 
> .. and this should check the frame for validity too.  At a minimum it
> should be properly aligned, but things like "it had better be above
> the current frame" to avoid having some loop would seem to be a good
> idea.

Makes sense.

> 
> Maybe even check that it's the same vma?

Hmm, I call on to Jens Remus and ask if s390 can do anything whacky here?
Where something that isn't allowed on other architectures may be allowed
there? I know s390 has some strange type of stack usage.

-- Steve