Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755485AbbDOAqR (ORCPT ); Tue, 14 Apr 2015 20:46:17 -0400 Received: from mail-ie0-f179.google.com ([209.85.223.179]:33609 "EHLO mail-ie0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753663AbbDOAqJ (ORCPT ); Tue, 14 Apr 2015 20:46:09 -0400 From: Roy Franz To: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, matt.fleming@intel.com, hpa@zytor.com, mingo@redhat.com, x86@kernel.org Cc: Roy Franz Subject: [PATCH] x86_64/efi: enforce 32 bit address for command line buffer Date: Tue, 14 Apr 2015 17:45:52 -0700 Message-Id: <1429058752-13478-1-git-send-email-roy.franz@linaro.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1983 Lines: 49 The boot_params structure has a 32 bit field for storing the address of the kernel command line. When the EFI stub allocates memory for the command line, it allocates at as low and address as possible, but does not ensure that the address of memory allocated is below 4G. This patch enforces this limit, and the stub now returns an error if the command line buffer is allocated at too high of an address. For 32 bit systems, the EFI mandated 1-1 memory mapping ensures that all memory is 32 bit addressable, so we don't have a problem. Also, mixed-mode booting on EFI platforms does not use the stub code, so we don't need to handle the case of booting a 32 bit kernel on a 64 bit EFI platform. Signed-off-by: Roy Franz --- arch/x86/boot/compressed/eboot.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c index ef17683..82dbe27 100644 --- a/arch/x86/boot/compressed/eboot.c +++ b/arch/x86/boot/compressed/eboot.c @@ -1108,6 +1108,19 @@ struct boot_params *make_boot_params(struct efi_config *c) cmdline_ptr = efi_convert_cmdline(sys_table, image, &options_size); if (!cmdline_ptr) goto fail; + +#ifdef CONFIG_X86_64 + /* + * hdr->cmd_line_ptr is a 32 bit field, so on 64 bit systems we need + * to ensure that the allocated buffer for the commandline is 32 bit + * addressable. + */ + if ((u64)(cmdline_ptr) + options_size > (u64)U32_MAX) { + efi_printk(sys_table, "Failed to alloc lowmem for command line\n"); + efi_free(sys_table, options_size, (unsigned long)cmdline_ptr); + goto fail; + } +#endif /* CONFIG_X86_64 */ hdr->cmd_line_ptr = (unsigned long)cmdline_ptr; hdr->ramdisk_image = 0; -- 1.9.1 -- 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/