From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753889AbbATLm4 (ORCPT ); Tue, 20 Jan 2015 06:42:56 -0500 Received: from terminus.zytor.com ([198.137.202.10]:56503 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751938AbbATLmy (ORCPT ); Tue, 20 Jan 2015 06:42:54 -0500 Date: Tue, 20 Jan 2015 03:42:35 -0800 From: tip-bot for Kees Cook Message-ID: Cc: whissi@whissi.de, bhe@redhat.com, vgoyal@redhat.com, keescook@chromium.org, hpa@zytor.com, JBeulich@suse.com, linux-kernel@vger.kernel.org, eternal.n08@gmail.com, ak@linux.intel.com, mingo@kernel.org, tglx@linutronix.de Reply-To: whissi@whissi.de, vgoyal@redhat.com, bhe@redhat.com, keescook@chromium.org, linux-kernel@vger.kernel.org, JBeulich@suse.com, hpa@zytor.com, ak@linux.intel.com, eternal.n08@gmail.com, mingo@kernel.org, tglx@linutronix.de In-Reply-To: <20150116005146.GA4212@www.outflux.net> References: <20150116005146.GA4212@www.outflux.net> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, boot: Skip relocs when load address unchanged Git-Commit-ID: f285f4a21c3253887caceed493089ece17579d59 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f285f4a21c3253887caceed493089ece17579d59 Gitweb: http://git.kernel.org/tip/f285f4a21c3253887caceed493089ece17579d59 Author: Kees Cook AuthorDate: Thu, 15 Jan 2015 16:51:46 -0800 Committer: Thomas Gleixner CommitDate: Tue, 20 Jan 2015 12:37:23 +0100 x86, boot: Skip relocs when load address unchanged On 64-bit, relocation is not required unless the load address gets changed. Without this, relocations do unexpected things when the kernel is above 4G. Reported-by: Baoquan He Signed-off-by: Kees Cook Tested-by: Thomas D. Cc: Vivek Goyal Cc: Jan Beulich Cc: Junjie Mao Cc: Andi Kleen Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net Signed-off-by: Thomas Gleixner --- arch/x86/boot/compressed/misc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index dcc1c53..a950864 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -373,6 +373,8 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, unsigned long output_len, unsigned long run_size) { + unsigned char *output_orig = output; + real_mode = rmode; sanitize_boot_params(real_mode); @@ -421,7 +423,12 @@ asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, debug_putstr("\nDecompressing Linux... "); decompress(input_data, input_len, NULL, NULL, output, NULL, error); parse_elf(output); - handle_relocations(output, output_len); + /* + * 32-bit always performs relocations. 64-bit relocations are only + * needed if kASLR has chosen a different load address. + */ + if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig) + handle_relocations(output, output_len); debug_putstr("done.\nBooting the kernel.\n"); return output; }