From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Daniel Axtens <dja@axtens.net>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kasan-dev@googlegroups.com, linux-mm@kvack.org
Subject: [PATCH v11 13/13] powerpc/32s: map kasan zero shadow with PAGE_READONLY instead of PAGE_KERNEL_RO
Date: Fri, 26 Apr 2019 16:23:37 +0000 (UTC) [thread overview]
Message-ID: <c829a8a1d366dc83cc7d8c9e00310230c5f21b4e.1556295461.git.christophe.leroy@c-s.fr> (raw)
In-Reply-To: <cover.1556295459.git.christophe.leroy@c-s.fr>
For hash32, the zero shadow page gets mapped with PAGE_READONLY instead
of PAGE_KERNEL_RO, because the PP bits don't provide a RO kernel, so
PAGE_KERNEL_RO is equivalent to PAGE_KERNEL. By using PAGE_READONLY,
the page is RO for both kernel and user, but this is not a security issue
as it contains only zeroes.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/mm/kasan/kasan_init_32.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c
index ba8361487075..0d62be3cba47 100644
--- a/arch/powerpc/mm/kasan/kasan_init_32.c
+++ b/arch/powerpc/mm/kasan/kasan_init_32.c
@@ -39,7 +39,10 @@ static int kasan_init_shadow_page_tables(unsigned long k_start, unsigned long k_
if (!new)
return -ENOMEM;
- kasan_populate_pte(new, PAGE_KERNEL_RO);
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ kasan_populate_pte(new, PAGE_READONLY);
+ else
+ kasan_populate_pte(new, PAGE_KERNEL_RO);
pmd_populate_kernel(&init_mm, pmd, new);
}
return 0;
@@ -84,7 +87,10 @@ static int __ref kasan_init_region(void *start, size_t size)
static void __init kasan_remap_early_shadow_ro(void)
{
- kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
+ if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_READONLY);
+ else
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL_RO);
flush_tlb_kernel_range(KASAN_SHADOW_START, KASAN_SHADOW_END);
}
--
2.13.3
prev parent reply other threads:[~2019-04-26 16:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 16:23 [PATCH v11 00/13] KASAN for powerpc/32 Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 01/13] powerpc/32: Move early_init() in a separate file Christophe Leroy
2019-05-03 6:59 ` Michael Ellerman
2019-04-26 16:23 ` [PATCH v11 02/13] powerpc: prepare string/mem functions for KASAN Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 03/13] powerpc: remove CONFIG_CMDLINE #ifdef mess Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 04/13] powerpc/prom_init: don't use string functions from lib/ Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 05/13] powerpc: don't use direct assignation during early boot Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 06/13] powerpc/32: use memset() instead of memset_io() to zero BSS Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 07/13] powerpc/32: make KVIRT_TOP dependent on FIXMAP_START Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 08/13] powerpc/32: prepare shadow area for KASAN Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 09/13] powerpc: disable KASAN instrumentation on early/critical files Christophe Leroy
2019-05-03 7:38 ` Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 10/13] powerpc/32: Add KASAN support Christophe Leroy
2019-05-03 6:51 ` Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 11/13] powerpc/32s: move hash code patching out of MMU_init_hw() Christophe Leroy
2019-04-26 16:23 ` [PATCH v11 12/13] powerpc/32s: set up an early static hash table for KASAN Christophe Leroy
2019-04-26 16:23 ` Christophe Leroy [this message]
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