From 5dcd14ecd41ea2b3ae3295a9b30d98769d52165f Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 29 Jan 2013 01:05:24 -0800 Subject: x86, boot: Sanitize boot_params if not zeroed on creation Use the new sentinel field to detect bootloaders which fail to follow protocol and don't initialize fields in struct boot_params that they do not explicitly initialize to zero. Based on an original patch and research by Yinghai Lu. Changed by hpa to be invoked both in the decompression path and in the kernel proper; the latter for the case where a bootloader takes over decompression. Originally-by: Yinghai Lu Link: http://lkml.kernel.org/r/1359058816-7615-26-git-send-email-yinghai@kernel.org Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/bootparam_utils.h | 38 ++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 arch/x86/include/asm/bootparam_utils.h (limited to 'arch/x86/include/asm/bootparam_utils.h') diff --git a/arch/x86/include/asm/bootparam_utils.h b/arch/x86/include/asm/bootparam_utils.h new file mode 100644 index 000000000000..5b5e9cb774b5 --- /dev/null +++ b/arch/x86/include/asm/bootparam_utils.h @@ -0,0 +1,38 @@ +#ifndef _ASM_X86_BOOTPARAM_UTILS_H +#define _ASM_X86_BOOTPARAM_UTILS_H + +#include + +/* + * This file is included from multiple environments. Do not + * add completing #includes to make it standalone. + */ + +/* + * Deal with bootloaders which fail to initialize unknown fields in + * boot_params to zero. The list fields in this list are taken from + * analysis of kexec-tools; if other broken bootloaders initialize a + * different set of fields we will need to figure out how to disambiguate. + * + */ +static void sanitize_boot_params(struct boot_params *boot_params) +{ + if (boot_params->sentinel) { + /*fields in boot_params are not valid, clear them */ + memset(&boot_params->olpc_ofw_header, 0, + (char *)&boot_params->alt_mem_k - + (char *)&boot_params->olpc_ofw_header); + memset(&boot_params->kbd_status, 0, + (char *)&boot_params->hdr - + (char *)&boot_params->kbd_status); + memset(&boot_params->_pad7[0], 0, + (char *)&boot_params->edd_mbr_sig_buffer[0] - + (char *)&boot_params->_pad7[0]); + memset(&boot_params->_pad8[0], 0, + (char *)&boot_params->eddbuf[0] - + (char *)&boot_params->_pad8[0]); + memset(&boot_params->_pad9[0], 0, sizeof(boot_params->_pad9)); + } +} + +#endif /* _ASM_X86_BOOTPARAM_UTILS_H */ -- cgit v1.2.1