[PATCH] Fix 'array subscript is above array bounds' warning in res_send.c

[Adhemerval Zanella]

On 16-12-2014 11:44, Siddhesh Poyarekar wrote:
> On Tue, Dec 16, 2014 at 11:12:24AM -0200, Adhemerval Zanella wrote:
>> In this loop 'ns' is initialized to '0' and updated on a simple while with
>> 2 constraints.  Someone with more compiler background could correct me, but
>> I don't think this is really hard to compile evaluate that will fall
>> in 0 <= ns < MAXNS in all cases.
> Oh I see it now - N is initialized to EXT(statp).nscount, not NS :/
>
> I agree that this is a compiler issue.  Here's a patch that undoes the
> change I made and adds DIAG_IGNORE_NEEDS_COMMENT instead.  Does this
> look OK?
Looks ok, thanks!
>
> Siddhesh
>
> 	* resolv/res_send.c (__libc_res_nsend): Disable warning 'array
> 	subscript above bounds'.
>
> diff --git a/resolv/res_send.c b/resolv/res_send.c
> index 5a9882c..c35fb66 100644
> --- a/resolv/res_send.c
> +++ b/resolv/res_send.c
> @@ -429,9 +429,15 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen,
>  				while (ns < MAXNS
>  				       && EXT(statp).nsmap[ns] != MAXNS)
>  					ns++;
> -				if (ns >= MAXNS)
> +				if (ns == MAXNS)
>  					break;
> +				/* NS never exceeds MAXNS, but gcc 4.9 somehow
> +				   does not see this.  */
> +				DIAG_PUSH_NEEDS_COMMENT;
> +				DIAG_IGNORE_NEEDS_COMMENT (4.9,
> +							   "-Warray-bounds");
>  				EXT(statp).nsmap[ns] = n;
> +				DIAG_POP_NEEDS_COMMENT;
>  				map[n] = ns++;
>  			}
>  		EXT(statp).nscount = n;