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From: Andrey Konovalov <andreyknvl@google.com>
To: "Andrey Ryabinin" <aryabinin@virtuozzo.com>,
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Cc: Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
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	Chintan Pandya <cpandya@codeaurora.org>
Subject: [PATCH v1 05/16] khwasan: initialize shadow to 0xff
Date: Tue,  8 May 2018 19:20:51 +0200	[thread overview]
Message-ID: <7c1197bce60a0d18c178ab5f025c438afa84be21.1525798754.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1525798753.git.andreyknvl@google.com>
In-Reply-To: <cover.1525798753.git.andreyknvl@google.com>

A KHWASAN shadow memory cell contains a memory tag, that corresponds to
the tag in the top byte of the pointer, that points to that memory. The
native top byte value of kernel pointers is 0xff, so with KHWASAN we
need to initialize shadow memory to 0xff. This commit does that.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/mm/kasan_init.c | 16 ++++++++++++++--
 include/linux/kasan.h      |  8 ++++++++
 mm/kasan/common.c          |  3 ++-
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 12145874c02b..7a31e8ccbad2 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -44,6 +44,15 @@ static phys_addr_t __init kasan_alloc_zeroed_page(int node)
 	return __pa(p);
 }
 
+static phys_addr_t __init kasan_alloc_raw_page(int node)
+{
+	void *p = memblock_virt_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
+						  __pa(MAX_DMA_ADDRESS),
+						  MEMBLOCK_ALLOC_ACCESSIBLE,
+						  node);
+	return __pa(p);
+}
+
 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
 				      bool early)
 {
@@ -89,7 +98,9 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 
 	do {
 		phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page)
-					      : kasan_alloc_zeroed_page(node);
+					      : kasan_alloc_raw_page(node);
+		if (!early)
+			memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
 		next = addr + PAGE_SIZE;
 		set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 	} while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
@@ -139,6 +150,7 @@ asmlinkage void __init kasan_early_init(void)
 		KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
 	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
 	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
+
 	kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
 			   true);
 }
@@ -235,7 +247,7 @@ void __init kasan_init(void)
 		set_pte(&kasan_zero_pte[i],
 			pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
 
-	memset(kasan_zero_page, 0, PAGE_SIZE);
+	memset(kasan_zero_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 
 	/* At this point kasan is fully initialized. Enable error messages */
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 6608aa9b35ac..336385baf926 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -139,6 +139,8 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 
 #ifdef CONFIG_KASAN_GENERIC
 
+#define KASAN_SHADOW_INIT 0
+
 void kasan_cache_shrink(struct kmem_cache *cache);
 void kasan_cache_shutdown(struct kmem_cache *cache);
 
@@ -149,4 +151,10 @@ static inline void kasan_cache_shutdown(struct kmem_cache *cache) {}
 
 #endif /* CONFIG_KASAN_GENERIC */
 
+#ifdef CONFIG_KASAN_HW
+
+#define KASAN_SHADOW_INIT 0xFF
+
+#endif /* CONFIG_KASAN_HW */
+
 #endif /* LINUX_KASAN_H */
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index ebb48415e4cf..0c1159feaf5e 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -454,11 +454,12 @@ int kasan_module_alloc(void *addr, size_t size)
 
 	ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
 			shadow_start + shadow_size,
-			GFP_KERNEL | __GFP_ZERO,
+			GFP_KERNEL,
 			PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
 			__builtin_return_address(0));
 
 	if (ret) {
+		__memset(ret, KASAN_SHADOW_INIT, shadow_size);
 		find_vm_area(addr)->flags |= VM_KASAN;
 		kmemleak_ignore(ret);
 		return 0;
-- 
2.17.0.441.gb46fe60e1d-goog

  parent reply	other threads:[~2018-05-08 17:20 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-08 17:20 [PATCH v1 00/16] khwasan: kernel hardware assisted address sanitizer Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 01/16] khwasan, mm: change kasan hooks signatures Andrey Konovalov
2018-05-14 16:56   ` Andrey Ryabinin
2018-05-08 17:20 ` [PATCH v1 02/16] khwasan: move common kasan and khwasan code to common.c Andrey Konovalov
2018-05-15 13:28   ` Andrey Ryabinin
2018-05-08 17:20 ` [PATCH v1 03/16] khwasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_HW Andrey Konovalov
2018-05-14 16:57   ` Andrey Ryabinin
2018-05-08 17:20 ` [PATCH v1 04/16] khwasan, arm64: adjust shadow size for CONFIG_KASAN_HW Andrey Konovalov
2018-05-08 17:20 ` Andrey Konovalov [this message]
2018-05-08 17:20 ` [PATCH v1 06/16] khwasan, arm64: untag virt address in __kimg_to_phys Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 07/16] khwasan, arm64: fix up fault handling logic Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 08/16] khwasan: add tag related helper functions Andrey Konovalov
2018-05-14 16:58   ` Andrey Ryabinin
2018-05-08 17:20 ` [PATCH v1 09/16] khwasan, arm64: enable top byte ignore for the kernel Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 10/16] khwasan, mm: perform untagged pointers comparison in krealloc Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 11/16] khwasan: split out kasan_report.c from report.c Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 12/16] khwasan: add bug reporting routines Andrey Konovalov
2018-05-08 17:20 ` [PATCH v1 13/16] khwasan: add hooks implementation Andrey Konovalov
2018-05-15 13:13   ` Andrey Ryabinin
2018-05-08 17:21 ` [PATCH v1 14/16] khwasan, arm64: add brk handler for inline instrumentation Andrey Konovalov
2018-05-08 17:21 ` [PATCH v1 15/16] khwasan, mm, arm64: tag non slab memory allocated via pagealloc Andrey Konovalov
2018-05-15 14:06   ` Andrey Ryabinin
2018-05-08 17:21 ` [PATCH v1 16/16] khwasan: update kasan documentation Andrey Konovalov
2018-05-09  5:26   ` Mike Rapoport
2018-05-09 12:13     ` Andrey Konovalov

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