[PATCH 35/64] fortify: Detect struct member overflows in memmove() at compile-time
From: Kees Cook <hidden>
Date: 2021-07-27 21:19:26
Also in:
dri-devel, linux-hardening, linux-kbuild, linux-staging, linux-wireless, lkml, netdev
Subsystem:
fortify_source, library code, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Kees Cook, Andrew Morton, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
As done for memcpy(), also update memmove() to use the same tightened compile-time checks under CONFIG_FORTIFY_SOURCE. Signed-off-by: Kees Cook <redacted> --- arch/x86/boot/compressed/misc.c | 3 ++- arch/x86/lib/memcpy_32.c | 1 + include/linux/fortify-string.h | 21 ++++--------------- .../read_overflow2_field-memmove.c | 5 +++++ .../write_overflow_field-memmove.c | 5 +++++ 5 files changed, 17 insertions(+), 18 deletions(-) create mode 100644 lib/test_fortify/read_overflow2_field-memmove.c create mode 100644 lib/test_fortify/write_overflow_field-memmove.c
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 743f13ea25c1..83ff4354970e 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c@@ -34,10 +34,11 @@ * try to define their own functions if these are not defined as macros. */ #define memzero(s, n) memset((s), 0, (n)) +#ifndef memmove #define memmove memmove - /* Functions used by the included decompressor code below. */ void *memmove(void *dest, const void *src, size_t n); +#endif /* * This is set up by the setup-routine at boot-time
diff --git a/arch/x86/lib/memcpy_32.c b/arch/x86/lib/memcpy_32.c
index e565d1c9019e..f19b7fd07f04 100644
--- a/arch/x86/lib/memcpy_32.c
+++ b/arch/x86/lib/memcpy_32.c@@ -4,6 +4,7 @@ #undef memcpy #undef memset +#undef memmove __visible void *memcpy(void *to, const void *from, size_t n) {
diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index 5e79e626172b..2ffa5224aaac 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h@@ -284,22 +284,10 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ memcpy) - -__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size) -{ - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); - - if (__builtin_constant_p(size)) { - if (p_size < size) - __write_overflow(); - if (q_size < size) - __read_overflow2(); - } - if (p_size < size || q_size < size) - fortify_panic(__func__); - return __underlying_memmove(p, q, size); -} +#define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ + __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ + __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ + memmove) extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); __FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
@@ -385,7 +373,6 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q) /* Don't use these outside the FORITFY_SOURCE implementation */ #undef __underlying_memchr #undef __underlying_memcmp -#undef __underlying_memmove #undef __underlying_memset #undef __underlying_strcat #undef __underlying_strcpy
diff --git a/lib/test_fortify/read_overflow2_field-memmove.c b/lib/test_fortify/read_overflow2_field-memmove.c
new file mode 100644
index 000000000000..6cc2724c8f62
--- /dev/null
+++ b/lib/test_fortify/read_overflow2_field-memmove.c@@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memmove(large, instance.buf, sizeof(instance.buf) + 1) + +#include "test_fortify.h"
diff --git a/lib/test_fortify/write_overflow_field-memmove.c b/lib/test_fortify/write_overflow_field-memmove.c
new file mode 100644
index 000000000000..377fcf9bb2fd
--- /dev/null
+++ b/lib/test_fortify/write_overflow_field-memmove.c@@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define TEST \ + memmove(instance.buf, large, sizeof(instance.buf) + 1) + +#include "test_fortify.h"
--
2.30.2