From 7f1e541fc8d57a143dd5df1d0a1276046e08c083 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 1 Feb 2018 21:00:49 +0300 Subject: [PATCH] compiler.h: Add read_word_at_a_time() function. Sometimes we know that it's safe to do potentially out-of-bounds access because we know it won't cross a page boundary. Still, KASAN will report this as a bug. Add read_word_at_a_time() function which is supposed to be used in such cases. In read_word_at_a_time() KASAN performs relaxed check - only the first byte of access is validated. Signed-off-by: Andrey Ryabinin Signed-off-by: Linus Torvalds --- include/linux/compiler.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 3035990a8070..c2cc57a2f508 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -238,6 +238,7 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s * required ordering. */ #include +#include #define __READ_ONCE(x, check) \ ({ \ @@ -257,6 +258,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s */ #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) +static __no_kasan_or_inline +unsigned long read_word_at_a_time(const void *addr) +{ + kasan_check_read(addr, 1); + return *(unsigned long *)addr; +} + #define WRITE_ONCE(x, val) \ ({ \ union { typeof(x) __val; char __c[1]; } __u = \