From: Guenter Roeck linux@roeck-us.net
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 torvalds@linux-foundation.org Reviewed-by: Geert Uytterhoeven geert@linux-m68k.org Acked-by: Andy Shevchenko andriy.shevchenko@intel.com Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/string.h | 19 ++----------------- lib/string_helpers.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+), 17 deletions(-)
--- a/include/linux/string.h +++ b/include/linux/string.h @@ -262,23 +262,8 @@ void __write_overflow(void) __compiletim #include <linux/fortify-string.h> #endif
-/** - * 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);
/** * str_has_prefix - Test if a string has a given prefix --- a/lib/string_helpers.c +++ b/lib/string_helpers.c @@ -696,3 +696,23 @@ void kfree_strarray(char **array, size_t kfree(array); } EXPORT_SYMBOL_GPL(kfree_strarray); + +/** + * 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. + */ +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); + } +} +EXPORT_SYMBOL(memcpy_and_pad);