linux-kernel - Re: [PATCH v7 07/10] vsprintf: Consolidate handling of unknown pointer specifiers

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Date:   Thu, 18 Apr 2019 23:43:56 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Tobin C . Harding" <me@...in.cc>, Joe Perches <joe@...ches.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.cz>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 07/10] vsprintf: Consolidate handling of unknown
 pointer specifiers

On (04/17/19 13:53), Petr Mladek wrote:
[..]
>  char *ip_addr_string(char *buf, char *end, const void *ptr,
>  		     struct printf_spec spec, const char *fmt)
>  {
> +	char *err_fmt_msg;
> +
>  	switch (fmt[1]) {
>  	case '6':
>  		return ip6_addr_string(buf, end, ptr, spec, fmt);
> @@ -1457,7 +1459,8 @@ char *ip_addr_string(char *buf, char *end, const void *ptr,
>  		}}
>  	}
>  
> -	return ptr_to_id(buf, end, ptr, spec);
> +	err_fmt_msg = fmt[0] == 'i' ? "(%pi?)" : "(%pI?)";
> +	return string_nocheck(buf, end, err_fmt_msg, spec);
>  }

We cannot err on fmt[0] here, can we. Both %pi and %pI are OK
and handled by pointer():

	switch (fmt[0]) {
	case 'I':
	case 'i':
		return ip_addr_string(buf, end, ptr, spec, fmt);


It's fmt[1] which can be unrecognized:

	switch (fmt[1]) {
	case '6':
	case '4':
	case 'S':
	}

	-ss