diff options
| author | Andrey Ryabinin <aryabinin@virtuozzo.com> | 2016-01-11 15:51:18 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-05 15:44:27 +0100 |
| commit | 2b24fe5c57af4d20650e1c3157305459fc5f4afc (patch) | |
| tree | 945804de3dec34ab1653510df0e348c68c8aee3b | |
| parent | 755bd549d9328d6d1e949a0a213f9a78e84d11fc (diff) | |
x86/kasan: Clear kasan_zero_page after TLB flush
commit 69e0210fd01ff157d332102219aaf5c26ca8069b upstream.
Currently we clear kasan_zero_page before __flush_tlb_all(). This
works with current implementation of native_flush_tlb[_global]()
because it doesn't cause do any writes to kasan shadow memory.
But any subtle change made in native_flush_tlb*() could break this.
Also current code seems doesn't work for paravirt guests (lguest).
Only after the TLB flush we can be sure that kasan_zero_page is not
used as early shadow anymore (instrumented code will not write to it).
So it should cleared it only after the TLB flush.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Borislav 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/1452516679-32040-2-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Jamie Iles <jamie.iles@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/mm/kasan_init_64.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index 4e5ac46adc9d..81ec7c02f968 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -121,11 +121,16 @@ void __init kasan_init(void) kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), (void *)KASAN_SHADOW_END); - memset(kasan_zero_page, 0, PAGE_SIZE); - load_cr3(init_level4_pgt); __flush_tlb_all(); - init_task.kasan_depth = 0; + /* + * 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. + */ + memset(kasan_zero_page, 0, PAGE_SIZE); + + init_task.kasan_depth = 0; pr_info("KernelAddressSanitizer initialized\n"); } |