[PATCH] iconvdata: Fix invalid pointer arithmetic in ANSI_X3.110 module

[Paul Zimmermann]

       Hi Florian,

just curious: as long as we don't access the array though array[inptr+1],
it is not a problem to just compute inptr+1, no?

Paul

> From: Florian Weimer <fweimer@redhat.com>
> Date: Fri, 28 Nov 2025 12:13:46 +0100
> 
> The expression inptr + 1 can technically be invalid: if inptr == inend,
> inptr may point one element past the end of an array.
> 
> ---
>  iconvdata/ansi_x3.110.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/iconvdata/ansi_x3.110.c b/iconvdata/ansi_x3.110.c
> index c5506b13b8..94e6e6b745 100644
> --- a/iconvdata/ansi_x3.110.c
> +++ b/iconvdata/ansi_x3.110.c
> @@ -407,7 +407,7 @@ static const char from_ucs4[][2] =
>  	   is also available.  */					      \
>  	uint32_t ch2;							      \
>  									      \
> -	if (inptr + 1 >= inend)						      \
> +	if (inend - inptr <= 1)						      \
>  	  {								      \
>  	    /* The second character is not available.  */		      \
>  	    result = __GCONV_INCOMPLETE_INPUT;				      \
> 
> base-commit: 15de57024611ed6e668acbc440c5e360b0543374
> 
>