From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759834AbdJQI6J (ORCPT ); Tue, 17 Oct 2017 04:58:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:41091 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756340AbdJQI4q (ORCPT ); Tue, 17 Oct 2017 04:56:46 -0400 Date: Tue, 17 Oct 2017 10:56:43 +0200 From: Michal Hocko To: James Hogan Cc: Kees Cook , LKML , Linus Torvalds , Jiri Kosina , Al Viro , Oleg Nesterov , Ingo Molnar , Baoquan He , linux-metag@vger.kernel.org Subject: Re: [PATCH 1/2] fs, elf: drop MAP_FIXED usage from elf_map Message-ID: <20171017085643.wag7fsrqmhhnlr2f@dhcp22.suse.cz> References: <20171004075059.bbx7madwgwflb7ky@dhcp22.suse.cz> <20171016134446.19910-1-mhocko@kernel.org> <20171016134446.19910-2-mhocko@kernel.org> <20171016190047.76ry2inllsacd3pv@dhcp22.suse.cz> <20171016200208.GL15235@jhogan-linux> <20171017073748.gdzsfkh3mnfp455x@dhcp22.suse.cz> <20171017083556.GM15235@jhogan-linux> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171017083556.GM15235@jhogan-linux> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 17-10-17 09:35:57, James Hogan wrote: > On Tue, Oct 17, 2017 at 09:37:48AM +0200, Michal Hocko wrote: [...] > > This would be something like. I wanted to share elf_vm_mmap but didn't > > find a proper place to not cause include dependency hell so I balied out > > to c&p. > > --- > > diff --git a/arch/metag/kernel/process.c b/arch/metag/kernel/process.c > > index c4606ce743d2..b20596b4c4c2 100644 > > --- a/arch/metag/kernel/process.c > > +++ b/arch/metag/kernel/process.c > > @@ -378,6 +378,29 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu) > > > > #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE) > > > > +static unsigned long elf_vm_mmap(struct file *filep, unsigned long addr, > > + unsigned long size, int prot, int type, unsigned long off) > > +{ > > + unsigned long map_addr; > > + > > + /* > > + * If caller requests the mapping at a specific place, make sure we fail > > + * rather than potentially clobber an existing mapping which can have > > + * security consequences (e.g. smash over the stack area). > > + */ > > + map_addr = vm_mmap(filep, addr, size, prot, type & ~MAP_FIXED, off); > > + if (BAD_ADDR(map_addr)) > > + return map_addr; > > + > > + if ((type & MAP_FIXED) && map_addr != addr) { > > + pr_info("Uhuuh, elf segement at %p requested but the memory is mapped already\n", > > + (void*)addr); > > + return -EAGAIN; > > + } > > + > > + return map_addr; > > +} > > + > > unsigned long __metag_elf_map(struct file *filep, unsigned long addr, > > struct elf_phdr *eppnt, int prot, int type, > > unsigned long total_size) > > @@ -410,11 +433,11 @@ unsigned long __metag_elf_map(struct file *filep, unsigned long addr, > > */ > > if (total_size) { > > total_size = ELF_PAGEALIGN(total_size); > > - map_addr = vm_mmap(filep, addr, total_size, prot, type, off); > > + map_addr = elf_vm_mmap(filep, addr, total_size, prot, type, off); > > if (!BAD_ADDR(map_addr)) > > vm_munmap(map_addr+size, total_size-size); > > } else > > - map_addr = vm_mmap(filep, addr, size, prot, type, off); > > + map_addr = elf_vm_mmap(filep, addr, size, prot, type, off); > > > > if (!BAD_ADDR(map_addr) && tcm_tag != TCM_INVALID_TAG) { > > struct tcm_allocation *tcm; > > Yeh that looks reasonable to me. Thanks for double checking. I will make sure to CC you when reposting the patch after other concerns sort out. -- Michal Hocko SUSE Labs