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Subject[RFC/PATCH RESEND -next 03/21] x86: add kasan hooks fort memcpy/memmove/memset functions
Date
Since functions memset, memmove, memcpy are written in assembly,
compiler can't instrument memory accesses inside them.

This patch replaces these functions with our own instrumented
functions (kasan_mem*) for CONFIG_KASAN = y

In rare circumstances you may need to use the original functions,
in such case put #undef KASAN_HOOKS before includes.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
---
arch/x86/include/asm/string_32.h | 28 ++++++++++++++++++++++++++++
arch/x86/include/asm/string_64.h | 24 ++++++++++++++++++++++++
arch/x86/lib/Makefile | 2 ++
3 files changed, 54 insertions(+)

diff --git a/arch/x86/include/asm/string_32.h b/arch/x86/include/asm/string_32.h
index 3d3e835..a86615a 100644
--- a/arch/x86/include/asm/string_32.h
+++ b/arch/x86/include/asm/string_32.h
@@ -321,6 +321,32 @@ void *__constant_c_and_count_memset(void *s, unsigned long pattern,
: __memset_generic((s), (c), (count)))

#define __HAVE_ARCH_MEMSET
+
+#if defined(CONFIG_KASAN) && defined(KASAN_HOOKS)
+
+/*
+ * Since some of the following functions (memset, memmove, memcpy)
+ * are written in assembly, compiler can't instrument memory accesses
+ * inside them.
+ *
+ * To solve this issue we replace these functions with our own instrumented
+ * functions (kasan_mem*)
+ *
+ * In rare circumstances you may need to use the original functions,
+ * in such case put #undef KASAN_HOOKS before includes.
+ */
+
+#undef memcpy
+void *kasan_memset(void *ptr, int val, size_t len);
+void *kasan_memcpy(void *dst, const void *src, size_t len);
+void *kasan_memmove(void *dst, const void *src, size_t len);
+
+#define memcpy(dst, src, len) kasan_memcpy((dst), (src), (len))
+#define memset(ptr, val, len) kasan_memset((ptr), (val), (len))
+#define memmove(dst, src, len) kasan_memmove((dst), (src), (len))
+
+#else /* CONFIG_KASAN && KASAN_HOOKS */
+
#if (__GNUC__ >= 4)
#define memset(s, c, count) __builtin_memset(s, c, count)
#else
@@ -331,6 +357,8 @@ void *__constant_c_and_count_memset(void *s, unsigned long pattern,
: __memset((s), (c), (count)))
#endif

+#endif /* CONFIG_KASAN && KASAN_HOOKS */
+
/*
* find the first occurrence of byte 'c', or 1 past the area if none
*/
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 19e2c46..2af2dbe 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -63,6 +63,30 @@ char *strcpy(char *dest, const char *src);
char *strcat(char *dest, const char *src);
int strcmp(const char *cs, const char *ct);

+#if defined(CONFIG_KASAN) && defined(KASAN_HOOKS)
+
+/*
+ * Since some of the following functions (memset, memmove, memcpy)
+ * are written in assembly, compiler can't instrument memory accesses
+ * inside them.
+ *
+ * To solve this issue we replace these functions with our own instrumented
+ * functions (kasan_mem*)
+ *
+ * In rare circumstances you may need to use the original functions,
+ * in such case put #undef KASAN_HOOKS before includes.
+ */
+
+void *kasan_memset(void *ptr, int val, size_t len);
+void *kasan_memcpy(void *dst, const void *src, size_t len);
+void *kasan_memmove(void *dst, const void *src, size_t len);
+
+#define memcpy(dst, src, len) kasan_memcpy((dst), (src), (len))
+#define memset(ptr, val, len) kasan_memset((ptr), (val), (len))
+#define memmove(dst, src, len) kasan_memmove((dst), (src), (len))
+
+#endif /* CONFIG_KASAN && KASAN_HOOKS */
+
#endif /* __KERNEL__ */

#endif /* _ASM_X86_STRING_64_H */
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 4d4f96a..d82bc35 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -2,6 +2,8 @@
# Makefile for x86 specific library files.
#

+KASAN_SANITIZE_memcpy_32.o := n
+
inat_tables_script = $(srctree)/arch/x86/tools/gen-insn-attr-x86.awk
inat_tables_maps = $(srctree)/arch/x86/lib/x86-opcode-map.txt
quiet_cmd_inat_tables = GEN $@
--
1.8.5.5


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