linux-kernel - Re: [RESEND][PATCH] x86: don't destroy %rbp on kernel-mode faults

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: <20080627154607.GA15718@elte.hu>
Date:	Fri, 27 Jun 2008 17:46:07 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Vegard Nossum <vegard.nossum@...il.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Andi Kleen <andi@...stfloor.org>,
	Pekka Enberg <penberg@...helsinki.fi>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RESEND][PATCH] x86: don't destroy %rbp on kernel-mode faults


* Vegard Nossum <vegard.nossum@...il.com> wrote:

> >From the code:
> 
>     "B stepping K8s sometimes report an truncated RIP for IRET exceptions
>     returning to compat mode. Check for these here too."
> 
> The code then proceeds to truncate the upper 32 bits of %rbp. This means
> that when do_page_fault() is finally called, its prologue,
> 
>     do_page_fault:
>         push %rbp
>         movl %rsp, %rbp
> 
> will put the truncated base pointer on the stack. This means that the
> stack tracer will not be able to follow the base-pointer changes and
> will see all subsequent stack frames as unreliable.
> 
> This patch changes the code to use a different register (%rcx) for the
> checking and leaves %rbp untouched.

applied to tip/x86/debug - thanks Vegard!

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/