Add basic sanity checking for pathological "size" arguments to memcpy(). Besides the run-time checking benefit, this avoids GCC trying to be very smart about value range tracking[1] when CONFIG_PROFILE_ALL_BRANCHES=y but FORTIFY_SOURCE=n.
Additionally avoid duplicate memcpy definitions in page.h. Link: https://lore.kernel.org/all/202505191117.C094A90F88@keescook/ [1] Reported-by: kernel test robot <l...@intel.com> Closes: https://lore.kernel.org/all/202501040747.s3lyfvyq-...@intel.com/ Signed-off-by: Kees Cook <k...@kernel.org> --- v2: split this off to csky v1: https://lore.kernel.org/lkml/20250520163320.work.924-k...@kernel.org/ Cc: Guo Ren <guo...@kernel.org> Cc: Arnd Bergmann <a...@arndb.de> Cc: Geert Uytterhoeven <ge...@linux-m68k.org> Cc: Stafford Horne <sho...@gmail.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: "Mike Rapoport (IBM)" <r...@kernel.org> Cc: Yan Zhao <yan.y.z...@intel.com> Cc: Linus Walleij <linus.wall...@linaro.org> Cc: Vincenzo Frascino <vincenzo.frasc...@arm.com> Cc: <linux-csky@vger.kernel.org> --- arch/csky/abiv1/inc/abi/string.h | 11 +++++++++++ arch/csky/abiv2/inc/abi/string.h | 11 +++++++++++ arch/csky/include/asm/page.h | 4 +--- 3 files changed, 23 insertions(+), 3 deletions(-) diff --git a/arch/csky/abiv1/inc/abi/string.h b/arch/csky/abiv1/inc/abi/string.h index de50117b904d..9e780877d8ab 100644 --- a/arch/csky/abiv1/inc/abi/string.h +++ b/arch/csky/abiv1/inc/abi/string.h @@ -6,6 +6,17 @@ #define __HAVE_ARCH_MEMCPY extern void *memcpy(void *, const void *, __kernel_size_t); +#ifndef CONFIG_FORTIFY_SOURCE +#define memcpy(t, f, n) \ + ({ \ + typeof(n) __n = (n); \ + /* Skip impossible sizes. */ \ + if (!(__n < 0 || __n == SIZE_MAX)) \ + __builtin_memcpy(t, f, __n); \ + (t); \ + }) +#endif /* !CONFIG_FORTIFY_SOURCE */ + #define __HAVE_ARCH_MEMMOVE extern void *memmove(void *, const void *, __kernel_size_t); diff --git a/arch/csky/abiv2/inc/abi/string.h b/arch/csky/abiv2/inc/abi/string.h index f01bad2ac4fb..e66d5d2f7e52 100644 --- a/arch/csky/abiv2/inc/abi/string.h +++ b/arch/csky/abiv2/inc/abi/string.h @@ -9,6 +9,17 @@ extern int memcmp(const void *, const void *, __kernel_size_t); #define __HAVE_ARCH_MEMCPY extern void *memcpy(void *, const void *, __kernel_size_t); +#ifndef CONFIG_FORTIFY_SOURCE +#define memcpy(t, f, n) \ + ({ \ + typeof(n) __n = (n); \ + /* Skip impossible sizes. */ \ + if (!(__n < 0 || __n == SIZE_MAX)) \ + __builtin_memcpy(t, f, __n); \ + (t); \ + }) +#endif /* !CONFIG_FORTIFY_SOURCE */ + #define __HAVE_ARCH_MEMMOVE extern void *memmove(void *, const void *, __kernel_size_t); diff --git a/arch/csky/include/asm/page.h b/arch/csky/include/asm/page.h index 4911d0892b71..069971389ce6 100644 --- a/arch/csky/include/asm/page.h +++ b/arch/csky/include/asm/page.h @@ -5,6 +5,7 @@ #include <asm/setup.h> #include <asm/cache.h> +#include <asm/string.h> #include <linux/const.h> #include <vdso/page.h> @@ -33,9 +34,6 @@ #define virt_addr_valid(kaddr) ((void *)(kaddr) >= (void *)PAGE_OFFSET && \ (void *)(kaddr) < high_memory) -extern void *memset(void *dest, int c, size_t l); -extern void *memcpy(void *to, const void *from, size_t l); - #define clear_page(page) memset((page), 0, PAGE_SIZE) #define copy_page(to, from) memcpy((to), (from), PAGE_SIZE) -- 2.34.1
