From 3942bb49728ad9e1f94d953a88af169a8f5d8099 Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Wed, 14 Aug 2024 13:00:34 +0300 Subject: string: add mem_is_zero() helper to check if memory area is all zeros Almost two thirds of the memchr_inv() usages check if the memory area is all zeros, with no interest in where in the buffer the first non-zero byte is located. Checking for !memchr_inv(s, 0, n) is also not very intuitive or discoverable. Add an explicit mem_is_zero() helper for this use case. Reviewed-by: Kees Cook Reviewed-by: Andy Shevchenko Link: https://patchwork.freedesktop.org/patch/msgid/20240814100035.3100852-1-jani.nikula@intel.com Signed-off-by: Jani Nikula --- include/linux/string.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 9edace076ddb..5855c5626b4b 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -279,6 +279,18 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt) void *memchr_inv(const void *s, int c, size_t n); char *strreplace(char *str, char old, char new); +/** + * mem_is_zero - Check if an area of memory is all 0's. + * @s: The memory area + * @n: The size of the area + * + * Return: True if the area of memory is all 0's. + */ +static inline bool mem_is_zero(const void *s, size_t n) +{ + return !memchr_inv(s, 0, n); +} + extern void kfree_const(const void *x); extern char *kstrdup(const char *s, gfp_t gfp) __malloc; -- cgit v1.2.3 From 559048d156ff3391c4b793779a824c9193e20442 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Mon, 5 Aug 2024 14:43:44 -0700 Subject: string: Check for "nonstring" attribute on strscpy() arguments GCC already checks for arguments that are marked with the "nonstring"[1] attribute when used on standard C String API functions (e.g. strcpy). Gain this compile-time checking also for the kernel's primary string copying function, strscpy(). Note that Clang has neither "nonstring" nor __builtin_has_attribute(). Link: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute [1] Reviewed-by: Miguel Ojeda Tested-by: Miguel Ojeda Link: https://lore.kernel.org/r/20240805214340.work.339-kees@kernel.org Signed-off-by: Kees Cook --- include/linux/string.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 9edace076ddb..95b3fc308f4f 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -76,12 +76,16 @@ ssize_t sized_strscpy(char *, const char *, size_t); * known size. */ #define __strscpy0(dst, src, ...) \ - sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst)) -#define __strscpy1(dst, src, size) sized_strscpy(dst, src, size) + sized_strscpy(dst, src, sizeof(dst) + __must_be_array(dst) + \ + __must_be_cstr(dst) + __must_be_cstr(src)) +#define __strscpy1(dst, src, size) \ + sized_strscpy(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src)) #define __strscpy_pad0(dst, src, ...) \ - sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst)) -#define __strscpy_pad1(dst, src, size) sized_strscpy_pad(dst, src, size) + sized_strscpy_pad(dst, src, sizeof(dst) + __must_be_array(dst) + \ + __must_be_cstr(dst) + __must_be_cstr(src)) +#define __strscpy_pad1(dst, src, size) \ + sized_strscpy_pad(dst, src, size + __must_be_cstr(dst) + __must_be_cstr(src)) /** * strscpy - Copy a C-string into a sized buffer -- cgit v1.2.3 From f69e63756f7822fcdad8a34f9967e8b243e883ee Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Wed, 2 Oct 2024 18:31:47 +0100 Subject: printf: Remove unused 'bprintf' bprintf() is unused. Remove it. It was added in the commit 4370aa4aa753 ("vsprintf: add binary printf") but as far as I can see was never used, unlike the other two functions in that patch. Link: https://lore.kernel.org/20241002173147.210107-1-linux@treblig.org Reviewed-by: Andy Shevchenko Acked-by: Petr Mladek Signed-off-by: Dr. David Alan Gilbert Signed-off-by: Steven Rostedt (Google) --- include/linux/string.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 0dd27afcfaf7..493ac4862c77 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -335,7 +335,6 @@ int __sysfs_match_string(const char * const *array, size_t n, const char *s); #ifdef CONFIG_BINARY_PRINTF int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args); int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf); -int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); #endif extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, -- cgit v1.2.3