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Message-Id: <20180509200223.22451-5-keescook@chromium.org>
Date: Wed, 9 May 2018 13:02:21 -0700
From: Kees Cook <keescook@...omium.org>
To: Matthew Wilcox <mawilcox@...rosoft.com>
Cc: Kees Cook <keescook@...omium.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Matthew Wilcox <willy@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Linux-MM <linux-mm@...ck.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: [PATCH v2 4/6] mm: Use overflow helpers in kmalloc_array*()
Instead of open-coded multiplication and bounds checking, use the new
overflow helper.
Signed-off-by: Kees Cook <keescook@...omium.org>
---
include/linux/slab.h | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 81ebd71f8c03..4d759e1ddc33 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -13,6 +13,7 @@
#define _LINUX_SLAB_H
#include <linux/gfp.h>
+#include <linux/overflow.h>
#include <linux/types.h>
#include <linux/workqueue.h>
@@ -624,11 +625,13 @@ int memcg_update_all_caches(int num_memcgs);
*/
static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
{
- if (size != 0 && n > SIZE_MAX / size)
+ size_t bytes;
+
+ if (unlikely(check_mul_overflow(n, size, &bytes)))
return NULL;
if (__builtin_constant_p(n) && __builtin_constant_p(size))
- return kmalloc(n * size, flags);
- return __kmalloc(n * size, flags);
+ return kmalloc(bytes, flags);
+ return __kmalloc(bytes, flags);
}
/**
@@ -657,11 +660,13 @@ extern void *__kmalloc_track_caller(size_t, gfp_t, unsigned long);
static inline void *kmalloc_array_node(size_t n, size_t size, gfp_t flags,
int node)
{
- if (size != 0 && n > SIZE_MAX / size)
+ size_t bytes;
+
+ if (unlikely(check_mul_overflow(n, size, &bytes)))
return NULL;
if (__builtin_constant_p(n) && __builtin_constant_p(size))
- return kmalloc_node(n * size, flags, node);
- return __kmalloc_node(n * size, flags, node);
+ return kmalloc_node(bytes, flags, node);
+ return __kmalloc_node(bytes, flags, node);
}
static inline void *kcalloc_node(size_t n, size_t size, gfp_t flags, int node)
--
2.17.0
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