From 434a6c9f90f7ab5ade619455df01ef5ebea533ee Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 9 May 2016 13:22:04 -0700 Subject: [PATCH] x86/KASLR: Initialize mapping_info every time As it turns out, mapping_info DOES need to be initialized every time, because pgt_data address could be changed during kernel relocation. So it can not be build time assigned. Without this, page tables were not being corrected updated, which could cause reboots when a physical address beyond 2G was chosen. Signed-off-by: Kees Cook Cc: Andrew Morton Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Baoquan He Cc: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Young Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vivek Goyal Cc: Yinghai Lu Cc: kernel-hardening@lists.openwall.com Cc: lasse.collin@tukaani.org Link: http://lkml.kernel.org/r/1462825332-10505-2-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/pagetable.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c index 3c99051566a9..34b95df14e69 100644 --- a/arch/x86/boot/compressed/pagetable.c +++ b/arch/x86/boot/compressed/pagetable.c @@ -89,17 +89,6 @@ static void prepare_level4(void) } } -/* - * Mapping information structure passed to kernel_ident_mapping_init(). - * Since this never changes, there's no reason to repeatedly fill it - * in on the stack when calling add_identity_map(). - */ -static struct x86_mapping_info mapping_info = { - .alloc_pgt_page = alloc_pgt_page, - .context = &pgt_data, - .pmd_flag = __PAGE_KERNEL_LARGE_EXEC, -}; - /* * Adds the specified range to what will become the new identity mappings. * Once all ranges have been added, the new mapping is activated by calling @@ -107,6 +96,11 @@ static struct x86_mapping_info mapping_info = { */ void add_identity_map(unsigned long start, unsigned long size) { + struct x86_mapping_info mapping_info = { + .alloc_pgt_page = alloc_pgt_page, + .context = &pgt_data, + .pmd_flag = __PAGE_KERNEL_LARGE_EXEC, + }; unsigned long end = start + size; /* Make sure we have a top level page table ready to use. */ -- 2.20.1