Re: [PATCH v1] x86: Fix bug in strncmp-evex and strncmp-avx2 [BZ #28895]

[Andreas Schwab <schwab@linux-m68k.org>]

On Feb 15 2022, Noah Goldstein via Libc-alpha wrote:

> diff --git a/string/test-strncmp.c b/string/test-strncmp.c
> index 831cb77893..501055de0c 100644
> --- a/string/test-strncmp.c
> +++ b/string/test-strncmp.c
> @@ -423,6 +423,29 @@ check3 (void)
>  	}
>  }
>  
> +
> +static void
> +check4 (void)
> +{
> +  /* To trigger bug 28895; We need 1) both s1 and s2 to be within 32 bytes of
> +     the end of the page. 2) For there to be no mismatch/null byte before the
> +     first page cross. 3) For length (`n`) to be large enough for one string to
> +     cross the page. And 4) for there to be either mismatch/null bytes before
> +     the start of the strings.  */
> +
> +  size_t size = 10;
> +  CHAR *s1 = (CHAR *)(buf1 + (getpagesize () & 0xffa) / sizeof (CHAR));
> +  CHAR *s2 = (CHAR *)(buf2 + (getpagesize () & 0xfed) / sizeof (CHAR));

s/&/-/

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."