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16 July 2024, 22:04:21 UTC
Revision e6bc8833d80fb695515a8144aa1dc13468db9d4d authored by Alexander Potapenko on 27 February 2023, 15:44:58 UTC, committed by Alexander Potapenko on 19 June 2023, 08:56:03 UTC 
string: use __builtin_memcpy() in strlcpy/strlcat
 
lib/string.c is built with -ffreestanding, which prevents the compiler
from replacing certain functions with calls to their library versions.

On the other hand, this also prevents Clang and GCC from instrumenting
calls to memcpy() when building with KASAN, KCSAN or KMSAN:
 - KASAN normally replaces memcpy() with __asan_memcpy() with the
   additional cc-param,asan-kernel-mem-intrinsic-prefix=1;
 - KCSAN and KMSAN replace memcpy() with __tsan_memcpy() and
   __msan_memcpy() by default.

To let the tools catch memory accesses from strlcpy/strlcat, replace
the calls to memcpy() with __builtin_memcpy(), which KASAN, KCSAN and
KMSAN are able to replace even in -ffreestanding mode.

This preserves the behavior in normal builds (__builtin_memcpy() ends up
being replaced with memcpy()), and does not introduce new instrumentation
in unwanted places, as strlcpy/strlcat are already instrumented.

Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/
Acked-by: Kees Cook <keescook@chromium.org>
1 parent 11aac78
Raw File
Tip revision: e6bc8833d80fb695515a8144aa1dc13468db9d4d authored by Alexander Potapenko on 27 February 2023, 15:44:58 UTC
string: use __builtin_memcpy() in strlcpy/strlcat
Tip revision: e6bc883
gup_test.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __GUP_TEST_H
#define __GUP_TEST_H

#include <linux/types.h>

#define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_test)
#define PIN_FAST_BENCHMARK	_IOWR('g', 2, struct gup_test)
#define PIN_LONGTERM_BENCHMARK	_IOWR('g', 3, struct gup_test)
#define GUP_BASIC_TEST		_IOWR('g', 4, struct gup_test)
#define PIN_BASIC_TEST		_IOWR('g', 5, struct gup_test)
#define DUMP_USER_PAGES_TEST	_IOWR('g', 6, struct gup_test)
#define PIN_LONGTERM_TEST_START	_IOW('g', 7, struct pin_longterm_test)
#define PIN_LONGTERM_TEST_STOP	_IO('g', 8)
#define PIN_LONGTERM_TEST_READ	_IOW('g', 9, __u64)

#define GUP_TEST_MAX_PAGES_TO_DUMP		8

#define GUP_TEST_FLAG_DUMP_PAGES_USE_PIN	0x1

struct gup_test {
	__u64 get_delta_usec;
	__u64 put_delta_usec;
	__u64 addr;
	__u64 size;
	__u32 nr_pages_per_call;
	__u32 gup_flags;
	__u32 test_flags;
	/*
	 * Each non-zero entry is the number of the page (1-based: first page is
	 * page 1, so that zero entries mean "do nothing") from the .addr base.
	 */
	__u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];
};

#define PIN_LONGTERM_TEST_FLAG_USE_WRITE	1
#define PIN_LONGTERM_TEST_FLAG_USE_FAST		2

struct pin_longterm_test {
	__u64 addr;
	__u64 size;
	__u32 flags;
};

#endif	/* __GUP_TEST_H */
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