From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Sender: Vasiliy Kulikov Date: Wed, 7 Sep 2011 13:55:08 +0400 From: Vasiliy Kulikov Message-ID: <20110907095508.GA16114@albatros> References: <20110825171934.GA3044@albatros> <20110902182929.GA23848@openwall.com> <20110903111849.GA2743@albatros> <20110903235728.GD29169@openwall.com> <20110905124647.GA10247@albatros> <20110906050554.GA3889@openwall.com> <20110907090900.GA3910@albatros> <20110907093036.GA17693@openwall.com> <20110907093411.GA4752@albatros> <20110907094335.GA17834@openwall.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110907094335.GA17834@openwall.com> Subject: Re: [kernel-hardening] [RFC] x86, mm: start mmap allocation for libs from low addresses To: kernel-hardening@lists.openwall.com List-ID: Solar, On Wed, Sep 07, 2011 at 13:43 +0400, Solar Designer wrote: > On Wed, Sep 07, 2011 at 01:34:11PM +0400, Vasiliy Kulikov wrote: > > On Wed, Sep 07, 2011 at 13:30 +0400, Solar Designer wrote: > > > What if mmap_min_addr set really low, or is even 0? I think we want to > > > skip low addresses even if processes are permitted to use those. > > > (Permitted does not mean encouraged.) So how about ASCII_ARMOR_MIN_ADDR > > > 0x19000 (100 KB) when !CONFIG_VM86? > > > > Are you talking about safety with NULL pointer dereferencing? > > Yes. OK, fully agree. But why 100 KB? Probably 0x10000 (64 KB)? It looks nicer and not so magic. -- Vasiliy