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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id l25sm21778354pgn.47.2020.03.02.10.39.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Mar 2020 10:39:45 -0800 (PST) Date: Mon, 2 Mar 2020 10:39:44 -0800 From: Kees Cook To: Arvind Sankar Cc: "Tobin C . Harding" , Tycho Andersen , kernel-hardening@lists.openwall.com, Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] x86/mm/init_32: Stop printing the virtual memory layout Message-ID: <202003021039.257258E1B@keescook> References: <202002291534.ED372CC@keescook> <20200301002209.1304982-1-nivedita@alum.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200301002209.1304982-1-nivedita@alum.mit.edu> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 29, 2020 at 07:22:09PM -0500, Arvind Sankar wrote: > For security, don't display the kernel's virtual memory layout. > > Signed-off-by: Arvind Sankar If this needs a v3, I'd just list the commits I mentioned for further justification. But regardless: Acked-by: Kees Cook -Kees > --- > arch/x86/mm/init_32.c | 38 -------------------------------------- > 1 file changed, 38 deletions(-) > > diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c > index 23df4885bbed..8ae0272c1c51 100644 > --- a/arch/x86/mm/init_32.c > +++ b/arch/x86/mm/init_32.c > @@ -788,44 +788,6 @@ void __init mem_init(void) > x86_init.hyper.init_after_bootmem(); > > mem_init_print_info(NULL); > - printk(KERN_INFO "virtual kernel memory layout:\n" > - " fixmap : 0x%08lx - 0x%08lx (%4ld kB)\n" > - " cpu_entry : 0x%08lx - 0x%08lx (%4ld kB)\n" > -#ifdef CONFIG_HIGHMEM > - " pkmap : 0x%08lx - 0x%08lx (%4ld kB)\n" > -#endif > - " vmalloc : 0x%08lx - 0x%08lx (%4ld MB)\n" > - " lowmem : 0x%08lx - 0x%08lx (%4ld MB)\n" > - " .init : 0x%08lx - 0x%08lx (%4ld kB)\n" > - " .data : 0x%08lx - 0x%08lx (%4ld kB)\n" > - " .text : 0x%08lx - 0x%08lx (%4ld kB)\n", > - FIXADDR_START, FIXADDR_TOP, > - (FIXADDR_TOP - FIXADDR_START) >> 10, > - > - CPU_ENTRY_AREA_BASE, > - CPU_ENTRY_AREA_BASE + CPU_ENTRY_AREA_MAP_SIZE, > - CPU_ENTRY_AREA_MAP_SIZE >> 10, > - > -#ifdef CONFIG_HIGHMEM > - PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, > - (LAST_PKMAP*PAGE_SIZE) >> 10, > -#endif > - > - VMALLOC_START, VMALLOC_END, > - (VMALLOC_END - VMALLOC_START) >> 20, > - > - (unsigned long)__va(0), (unsigned long)high_memory, > - ((unsigned long)high_memory - (unsigned long)__va(0)) >> 20, > - > - (unsigned long)&__init_begin, (unsigned long)&__init_end, > - ((unsigned long)&__init_end - > - (unsigned long)&__init_begin) >> 10, > - > - (unsigned long)&_etext, (unsigned long)&_edata, > - ((unsigned long)&_edata - (unsigned long)&_etext) >> 10, > - > - (unsigned long)&_text, (unsigned long)&_etext, > - ((unsigned long)&_etext - (unsigned long)&_text) >> 10); > > /* > * Check boundaries twice: Some fundamental inconsistencies can > -- > 2.24.1 > -- Kees Cook