linux-kernel - [PATCH] kasan, fortify: properly rename memintrinsics

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Date: Fri, 17 May 2024 15:01:18 +0200
From: andrey.konovalov@...ux.dev
To: Marco Elver <elver@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	kasan-dev@...glegroups.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm@...ck.org,
	Erhard Furtner <erhard_f@...lbox.org>,
	Nico Pache <npache@...hat.com>,
	Daniel Axtens <dja@...ens.net>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] kasan, fortify: properly rename memintrinsics

From: Andrey Konovalov <andreyknvl@...il.com>

After commit 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*()
functions") and the follow-up fixes, with CONFIG_FORTIFY_SOURCE enabled,
even though the compiler instruments meminstrinsics by generating calls
to __asan/__hwasan_ prefixed functions, FORTIFY_SOURCE still uses
uninstrumented memset/memmove/memcpy as the underlying functions.

As a result, KASAN cannot detect bad accesses in memset/memmove/memcpy.
This also makes KASAN tests corrupt kernel memory and cause crashes.

To fix this, use __asan_/__hwasan_memset/memmove/memcpy as the underlying
functions whenever appropriate. Do this only for the instrumented code
(as indicated by __SANITIZE_ADDRESS__).

Reported-by: Erhard Furtner <erhard_f@...lbox.org>
Reported-by: Nico Pache <npache@...hat.com>
Closes: https://lore.kernel.org/all/20240501144156.17e65021@outsider.home/
Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Fixes: 51287dcb00cc ("kasan: emit different calls for instrumentable memintrinsics")
Fixes: 36be5cba99f6 ("kasan: treat meminstrinsic as builtins in uninstrumented files")
Signed-off-by: Andrey Konovalov <andreyknvl@...il.com>
---
 include/linux/fortify-string.h | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 85fc0e6f0f7f..bac010cfc42f 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -75,17 +75,30 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
 	__ret;							\
 })
 
-#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+#if defined(__SANITIZE_ADDRESS__)
+
+#if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
+#elif defined(CONFIG_KASAN_GENERIC)
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy);
+#else /* CONFIG_KASAN_SW_TAGS */
+extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset);
+extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove);
+extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy);
+#endif
+
 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
-extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
-extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
-extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
+
 #else
 
 #if defined(__SANITIZE_MEMORY__)
@@ -110,6 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
 #define __underlying_strlen	__builtin_strlen
 #define __underlying_strncat	__builtin_strncat
 #define __underlying_strncpy	__builtin_strncpy
+
 #endif
 
 /**
-- 
2.25.1