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From: Florian Weimer <fw@deneb.enyo.de>
To: Szabolcs Nagy via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [PATCH] Fix aliasing violation in __vfscanf_internal [BZ #26690]
References: <20201007175049.32564-1-szabolcs.nagy@arm.com>
Date: Wed, 07 Oct 2020 20:08:05 +0200
In-Reply-To: <20201007175049.32564-1-szabolcs.nagy@arm.com> (Szabolcs Nagy via
 Libc-alpha's message of "Wed, 7 Oct 2020 18:50:49 +0100")
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* Szabolcs Nagy via Libc-alpha:

> diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c
> index 95b46dcbeb..d832493623 100644
> --- a/stdio-common/vfscanf-internal.c
> +++ b/stdio-common/vfscanf-internal.c
> @@ -135,6 +135,16 @@
>  
>  #include "printf-parse.h" /* Use read_int.  */
>  
> +/* Same as read_int, but for CHAR_T * instead of UCHAR_T * string.  */
> +static int
> +read_int_char (const CHAR_T * *pstr)
> +{
> +  const UCHAR_T *ustr = (const UCHAR_T *) *pstr;
> +  int retval = read_int (&ustr);
> +  *pstr = (const CHAR_T *) ustr;
> +  return retval;
> +}
> +
>  #define encode_error() do {						      \
>  			  __set_errno (EILSEQ);				      \
>  			  goto errout;					      \
> @@ -486,7 +496,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
>        /* Check for a positional parameter specification.  */
>        if (ISDIGIT ((UCHAR_T) *f))
>  	{
> -	  argpos = read_int ((const UCHAR_T **) &f);
> +	  argpos = read_int_char (&f);
>  	  if (*f == L_('$'))
>  	    ++f;
>  	  else
> @@ -522,7 +532,7 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
>        /* Find the maximum field width.  */
>        width = 0;
>        if (ISDIGIT ((UCHAR_T) *f))
> -	width = read_int ((const UCHAR_T **) &f);
> +	width = read_int_char (&f);
>      got_width:
>        if (width == 0)
>  	width = -1;

Patch and commit message look reasonable to me.  Thanks.