linux-kernel - Re: [m68k:master 1174/1174] arch/m68k/include/asm/string.h:72:25: warning: '__builtin_memcpy' forming offset 8 is out of the bounds [0, 7]

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Message-ID: <alpine.LNX.2.21.1903071329140.513@nippy.intranet>
Date:   Thu, 7 Mar 2019 13:59:33 +1100 (AEDT)
From:   Finn Thain <fthain@...egraphics.com.au>
To:     Andreas Schwab <schwab@...ux-m68k.org>
cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        kbuild test robot <lkp@...el.com>, kbuild-all@...org,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [m68k:master 1174/1174] arch/m68k/include/asm/string.h:72:25:
 warning: '__builtin_memcpy' forming offset 8 is out of the bounds [0, 7]

On Tue, 5 Mar 2019, Andreas Schwab wrote:

> On Mar 05 2019, Finn Thain <fthain@...egraphics.com.au> wrote:
> 
> > interesting that the kernel's strlen implementation in 
> > include/linux/string.h can't achieve this.
> 
> This implementation is only available if ARCH_HAS_FORTIFY_SOURCE.
> 

I see. Perhaps we could add another definition to that file:

#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
...
#else
__FORTIFY_INLINE __kernel_size_t strlen(const char *p)
{
	return __builtin_strlen(p);
}
#endif

I didn't test that. But the following patch seems to work...

diff --git a/arch/m68k/include/asm/string.h b/arch/m68k/include/asm/string.h
index f759d944c449..3cff6b128ed3 100644
--- a/arch/m68k/include/asm/string.h
+++ b/arch/m68k/include/asm/string.h
@@ -71,4 +71,6 @@ extern void *memset(void *, int, __kernel_size_t);
 extern void *memcpy(void *, const void *, __kernel_size_t);
 #define memcpy(d, s, n) __builtin_memcpy(d, s, n)
 
+#define strlen(s) __builtin_strlen(s)
+
 #endif /* _M68K_STRING_H_ */
diff --git a/lib/string.c b/lib/string.c
index 38e4ca08e757..fe970f2160e5 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -472,6 +472,7 @@ char *strim(char *s)
 EXPORT_SYMBOL(strim);
 
 #ifndef __HAVE_ARCH_STRLEN
+#undef strlen
 /**
  * strlen - Find the length of a string
  * @s: The string to be sized

-- 

> Andreas.
> 
>