Commit-ID: 063fb3e56f6dd29b2633b678b837e1d904200e6f Gitweb: http://git.kernel.org/tip/063fb3e56f6dd29b2633b678b837e1d904200e6f Author: Andrey Ryabinin <aryabi...@virtuozzo.com> AuthorDate: Mon, 11 Jan 2016 15:51:19 +0300 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 9 Feb 2016 13:33:14 +0100
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: Andrey Ryabinin <aryabi...@virtuozzo.com> Reviewed-by: Borislav Petkov <b...@suse.de> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Luis R. Rodriguez <mcg...@suse.com> Cc: Oleg Nesterov <o...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Toshi Kani <toshi.k...@hp.com> Cc: linux...@kvack.org Link: http://lkml.kernel.org/r/1452516679-32040-3-git-send-email-aryabi...@virtuozzo.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/mm/kasan_init_64.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 303e470..1b1110f 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -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");
