Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758224AbbBFMbL (ORCPT ); Fri, 6 Feb 2015 07:31:11 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:41018 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755329AbbBFMCG (ORCPT ); Fri, 6 Feb 2015 07:02:06 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Kees Cook , Vivek Goyal , Jan Beulich , Junjie Mao , Andi Kleen , Thomas Gleixner , Luis Henriques Subject: [PATCH 3.16.y-ckt 043/135] x86, boot: Skip relocs when load address unchanged Date: Fri, 6 Feb 2015 12:00:21 +0000 Message-Id: <1423224113-10958-44-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> References: <1423224113-10958-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2204 Lines: 61 3.16.7-ckt6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit f285f4a21c3253887caceed493089ece17579d59 upstream. 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 Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net Signed-off-by: Thomas Gleixner Signed-off-by: Luis Henriques --- 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 30dd59a9f0b4..0c33a7c67ea5 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -361,6 +361,8 @@ 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); @@ -409,7 +411,12 @@ 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; } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/