From 02205a347c40cfbcc5ce34e4ecd63ea821221237 Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Mon, 14 Aug 2017 22:12:38 +0200 Subject: BACKPORT: string.h: add memcpy_and_pad() commit 01f33c336e2d298ea5d4ce5d6e5bcd12865cc30f upstream. This helper function is useful for the nvme subsystem, and maybe others. Note: the warnings reported by the kbuild test robot for this patch are actually generated by the use of CONFIG_PROFILE_ALL_BRANCHES together with __FORTIFY_INLINE. Change-Id: I5f7e1e9143ce9df88af0afd02aef971d5172bd3e Signed-off-by: Martin Wilck Reviewed-by: Sagi Grimberg Signed-off-by: Christoph Hellwig [AG: Backported to 4.4] Signed-off-by: Alexander Grund --- include/linux/string.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 1a9589a5ace6..84af888924e1 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -204,4 +204,33 @@ static inline const char *kbasename(const char *path) return tail ? tail + 1 : path; } +/** + * memcpy_and_pad - Copy one buffer to another with padding + * @dest: Where to copy to + * @dest_len: The destination buffer size + * @src: Where to copy from + * @count: The number of bytes to copy + * @pad: Character to use for padding if space is left in destination. + */ +__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len, + const void *src, size_t count, int pad) +{ + size_t dest_size = __builtin_object_size(dest, 0); + size_t src_size = __builtin_object_size(src, 0); + + if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) { + if (dest_size < dest_len && dest_size < count) + __write_overflow(); + else if (src_size < dest_len && src_size < count) + __read_overflow3(); + } + if (dest_size < dest_len) + fortify_panic(__func__); + if (dest_len > count) { + memcpy(dest, src, count); + memset(dest + count, pad, dest_len - count); + } else + memcpy(dest, src, dest_len); +} + #endif /* _LINUX_STRING_H_ */ -- cgit v1.2.3 From 603fe30acf57a20d48ceec9fccb78715f5d589c9 Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Wed, 6 Sep 2017 14:36:57 +0200 Subject: string.h: un-fortify memcpy_and_pad commit 1359798f9d4082eb04575efdd19512fbd9c28464 upstream. The way I'd implemented the new helper memcpy_and_pad with __FORTIFY_INLINE caused compiler warnings for certain kernel configurations. This helper is only used in a single place at this time, and thus doesn't benefit much from fortification. So simplify the code by dropping fortification support for now. Fixes: 01f33c336e2d "string.h: add memcpy_and_pad()" Change-Id: I8bb1ec4490e27d450ba2042074d6f228b102462a Signed-off-by: Martin Wilck Acked-by: Arnd Bergmann Signed-off-by: Christoph Hellwig Signed-off-by: Alexander Grund --- include/linux/string.h | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index 84af888924e1..c874f5ea9bb3 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -212,20 +212,9 @@ static inline const char *kbasename(const char *path) * @count: The number of bytes to copy * @pad: Character to use for padding if space is left in destination. */ -__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len, - const void *src, size_t count, int pad) +static inline void memcpy_and_pad(void *dest, size_t dest_len, + const void *src, size_t count, int pad) { - size_t dest_size = __builtin_object_size(dest, 0); - size_t src_size = __builtin_object_size(src, 0); - - if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) { - if (dest_size < dest_len && dest_size < count) - __write_overflow(); - else if (src_size < dest_len && src_size < count) - __read_overflow3(); - } - if (dest_size < dest_len) - fortify_panic(__func__); if (dest_len > count) { memcpy(dest, src, count); memset(dest + count, pad, dest_len - count); -- cgit v1.2.3 From 3d129c2c52ce9bb9af94364957b7a75758351c2b Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Tue, 2 Nov 2021 07:24:20 -0700 Subject: string: uninline memcpy_and_pad commit 5c4e0a21fae877a7ef89be6dcc6263ec672372b8 upstream. When building m68k:allmodconfig, recent versions of gcc generate the following error if the length of UTS_RELEASE is less than 8 bytes. In function 'memcpy_and_pad', inlined from 'nvmet_execute_disc_identify' at drivers/nvme/target/discovery.c:268:2: arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 8 bytes from a region of size 7 Discussions around the problem suggest that this only happens if an architecture does not provide strlen(), if -ffreestanding is provided as compiler option, and if CONFIG_FORTIFY_SOURCE=n. All of this is the case for m68k. The exact reasons are unknown, but seem to be related to the ability of the compiler to evaluate the return value of strlen() and the resulting execution flow in memcpy_and_pad(). It would be possible to work around the problem by using sizeof(UTS_RELEASE) instead of strlen(UTS_RELEASE), but that would only postpone the problem until the function is called in a similar way. Uninline memcpy_and_pad() instead to solve the problem for good. Suggested-by: Linus Torvalds Reviewed-by: Geert Uytterhoeven Acked-by: Andy Shevchenko Change-Id: I21516b6de0b5f3d8af30ebbbfcac2d4a495658ac Signed-off-by: Guenter Roeck Signed-off-by: Linus Torvalds Signed-off-by: Alexander Grund --- include/linux/string.h | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index c874f5ea9bb3..9f745d7e9f3f 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -204,22 +204,7 @@ static inline const char *kbasename(const char *path) return tail ? tail + 1 : path; } -/** - * memcpy_and_pad - Copy one buffer to another with padding - * @dest: Where to copy to - * @dest_len: The destination buffer size - * @src: Where to copy from - * @count: The number of bytes to copy - * @pad: Character to use for padding if space is left in destination. - */ -static inline void memcpy_and_pad(void *dest, size_t dest_len, - const void *src, size_t count, int pad) -{ - if (dest_len > count) { - memcpy(dest, src, count); - memset(dest + count, pad, dest_len - count); - } else - memcpy(dest, src, dest_len); -} +void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, + int pad); #endif /* _LINUX_STRING_H_ */ -- cgit v1.2.3