Commit 434a6c9f authored May 09, 2016 by Kees Cook Committed by Ingo Molnar May 10, 2016

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 <keescook@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
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 <mingo@kernel.org>

parent 36a39ac9

arch/x86/boot/compressed/pagetable.c

+5 −11

Original line number	Diff line number	Diff line
		@@ -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. */

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