[U-Boot] [PATCH v2 07/17] lib: vsprintf: correct printing of Unicode strings

[Alexander Graf]

On 31.08.18 21:31, Heinrich Schuchardt wrote:
> The width and precision of the printf() function refer to the number of
> characters not to the number of bytes printed.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> v2:
> 	use library function utf16_utf8_strncpy() for string16()
> ---
>  lib/vsprintf.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 5abf734750..4213441fbf 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -280,18 +280,13 @@ static char *string16(char *buf, char *end, u16 *s, int field_width,
>  		int precision, int flags)
>  {
>  	u16 *str = s ? s : L"<NULL>";
> -	int utf16_len = u16_strnlen(str, precision);
> -	u8 utf8[utf16_len * MAX_UTF8_PER_UTF16];
> -	int utf8_len, i;
> -
> -	utf8_len = utf16_to_utf8(utf8, str, utf16_len) - utf8;
> +	ssize_t len = utf16_strnlen(str, precision);
>  
>  	if (!(flags & LEFT))
> -		while (utf8_len < field_width--)
> +		for (; len < field_width; --field_width)
>  			ADDCH(buf, ' ');
> -	for (i = 0; i < utf8_len; ++i)
> -		ADDCH(buf, utf8[i]);
> -	while (utf8_len < field_width--)
> +	utf16_utf8_strncpy(&buf, str, len);
> +	for (; len < field_width; --field_width)
>  		ADDCH(buf, ' ');
>  	return buf;

Both the string() and string16() functions seem to completely ignore the
"end" variable. Doesn't that mean we're potentially running over the end
of a buffer with snprintf()?

I think the patch as is is fine, because string() has the same problem
and the previous version didn't bother either. But in the long run, we
should probably fix the end checks.


Alex