Commit 7c201739 authored by Marco Elver's avatar Marco Elver Committed by Paul E. McKenney
Browse files

kcsan: Instrument memcpy/memset/memmove with newer Clang 



With Clang version 16+, -fsanitize=thread will turn
memcpy/memset/memmove calls in instrumented functions into
__tsan_memcpy/__tsan_memset/__tsan_memmove calls respectively.

Add these functions to the core KCSAN runtime, so that we (a) catch data
races with mem* functions, and (b) won't run into linker errors with
such newer compilers.

Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: default avatarMarco Elver <elver@google.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 9abf2313

kernel/kcsan/core.c

+50 −0
Original line number Diff line number Diff line
@@ -14,10 +14,12 @@ 
#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/list.h>

#include <linux/minmax.h>

#include <linux/moduleparam.h>

#include <linux/percpu.h>

#include <linux/preempt.h>

#include <linux/sched.h>

#include <linux/string.h>

#include <linux/uaccess.h>



#include "encoding.h"
@@ -1308,3 +1310,51 @@ noinline void __tsan_atomic_signal_fence(int memorder) 
	}

}

EXPORT_SYMBOL(__tsan_atomic_signal_fence);



#ifdef __HAVE_ARCH_MEMSET

void *__tsan_memset(void *s, int c, size_t count);

noinline void *__tsan_memset(void *s, int c, size_t count)

{

	/*

	 * Instead of not setting up watchpoints where accessed size is greater

	 * than MAX_ENCODABLE_SIZE, truncate checked size to MAX_ENCODABLE_SIZE.

	 */

	size_t check_len = min_t(size_t, count, MAX_ENCODABLE_SIZE);



	check_access(s, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);

	return memset(s, c, count);

}

#else

void *__tsan_memset(void *s, int c, size_t count) __alias(memset);

#endif

EXPORT_SYMBOL(__tsan_memset);



#ifdef __HAVE_ARCH_MEMMOVE

void *__tsan_memmove(void *dst, const void *src, size_t len);

noinline void *__tsan_memmove(void *dst, const void *src, size_t len)

{

	size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);



	check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);

	check_access(src, check_len, 0, _RET_IP_);

	return memmove(dst, src, len);

}

#else

void *__tsan_memmove(void *dst, const void *src, size_t len) __alias(memmove);

#endif

EXPORT_SYMBOL(__tsan_memmove);



#ifdef __HAVE_ARCH_MEMCPY

void *__tsan_memcpy(void *dst, const void *src, size_t len);

noinline void *__tsan_memcpy(void *dst, const void *src, size_t len)

{

	size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);



	check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);

	check_access(src, check_len, 0, _RET_IP_);

	return memcpy(dst, src, len);

}

#else

void *__tsan_memcpy(void *dst, const void *src, size_t len) __alias(memcpy);

#endif

EXPORT_SYMBOL(__tsan_memcpy);