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Commit 063fb3e5 authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Ingo Molnar
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x86/kasan: Write protect kasan zero shadow 



After kasan_init() executed, no one is allowed to write to kasan_zero_page,
so write protect it.

Signed-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1452516679-32040-3-git-send-email-aryabinin@virtuozzo.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 69e0210f

arch/x86/mm/kasan_init_64.c

+8 −2
Original line number Diff line number Diff line
@@ -125,10 +125,16 @@ void __init kasan_init(void) 


	/*

	 * kasan_zero_page has been used as early shadow memory, thus it may

	 * contain some garbage. Now we can clear it, since after the TLB flush

	 * no one should write to it.

	 * contain some garbage. Now we can clear and write protect it, since

	 * after the TLB flush no one should write to it.

	 */

	memset(kasan_zero_page, 0, PAGE_SIZE);

	for (i = 0; i < PTRS_PER_PTE; i++) {

		pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);

		set_pte(&kasan_zero_pte[i], pte);

	}

	/* Flush TLBs again to be sure that write protection applied. */

	__flush_tlb_all();



	init_task.kasan_depth = 0;

	pr_info("KernelAddressSanitizer initialized\n");