From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergey Senozhatsky Subject: Re: [PATCH] vsprintf: Do not break early boot with probing addresses Date: Fri, 10 May 2019 14:07:09 +0900 Message-ID: <20190510050709.GA1831@jagdpanzerIV> References: <20190509121923.8339-1-pmladek@suse.com> <20190510043200.GC15652@jagdpanzerIV> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Linus Torvalds Cc: Sergey Senozhatsky , Petr Mladek , Andy Shevchenko , Rasmus Villemoes , "Tobin C . Harding" , Michal Hocko , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org, Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Russell Currey , Christophe Leroy , Stephen Rothwell , Heiko Carstens , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky List-Id: linux-arch.vger.kernel.org On (05/09/19 21:47), Linus Torvalds wrote: > [ Sorry about html and mobile crud, I'm not at the computer right now ] > How about we just undo the whole misguided probe_kernel_address() thing? But the problem will remain - %pS/%pF on PPC (and some other arch-s) do dereference_function_descriptor(), which calls probe_kernel_address(). So if probe_kernel_address() starts to dump_stack(), then we are heading towards stack overflow. Unless I'm totally missing something. -ss From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f195.google.com ([209.85.214.195]:45334 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726587AbfEJFHO (ORCPT ); Fri, 10 May 2019 01:07:14 -0400 Date: Fri, 10 May 2019 14:07:09 +0900 From: Sergey Senozhatsky Subject: Re: [PATCH] vsprintf: Do not break early boot with probing addresses Message-ID: <20190510050709.GA1831@jagdpanzerIV> References: <20190509121923.8339-1-pmladek@suse.com> <20190510043200.GC15652@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Linus Torvalds Cc: Sergey Senozhatsky , Petr Mladek , Andy Shevchenko , Rasmus Villemoes , "Tobin C . Harding" , Michal Hocko , Sergey Senozhatsky , Steven Rostedt , linux-kernel@vger.kernel.org, Michael Ellerman , linuxppc-dev@lists.ozlabs.org, Russell Currey , Christophe Leroy , Stephen Rothwell , Heiko Carstens , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky Message-ID: <20190510050709.ugUsmdWEg2-_zeuhzXY9dG3VOFvC7DcdjoUsQ1gSOxk@z> On (05/09/19 21:47), Linus Torvalds wrote: > [ Sorry about html and mobile crud, I'm not at the computer right now ] > How about we just undo the whole misguided probe_kernel_address() thing? But the problem will remain - %pS/%pF on PPC (and some other arch-s) do dereference_function_descriptor(), which calls probe_kernel_address(). So if probe_kernel_address() starts to dump_stack(), then we are heading towards stack overflow. Unless I'm totally missing something. -ss