netfilter: nf_conntrack_sctp: fix build warning

Wu Fengguang wrote:
> On Mon, Nov 24, 2008 at 02:23:16PM +0200, Patrick McHardy wrote:
>> +	/* Avoid bogus warning, gcc doesn't realize do_basic_checks()
>> +	 * guarantees that there is at least one SCTP chunk.
>> +	 */
>> +	if (unlikely(new_state == SCTP_CONNTRACK_MAX))
>> +		goto out;
>> +
> 
> If do_basic_checks() guarantees that, why not Initialize new_state to 0?

Good point. I've replaced the patch by this one:
commit 328bd8997dbb7184d5389e45c642af44ae6e9043
Author: Patrick McHardy <kaber@trash.net>
Date:   Mon Nov 24 13:44:55 2008 +0100

    netfilter: nf_conntrack_proto_sctp: avoid bogus warning
    
    net/netfilter/nf_conntrack_proto_sctp.c: In function 'sctp_packet':
    net/netfilter/nf_conntrack_proto_sctp.c:376: warning: array subscript is above array bounds
    
    gcc doesn't realize that do_basic_checks() guarantees that there is
    at least one valid chunk and thus new_state is never SCTP_CONNTRACK_MAX
    after the loop. Initialize to SCTP_CONNTRACK_NONE to avoid the warning.
    
    Based on patch by Wu Fengguang <wfg@linux.intel.com>
    
    Signed-off-by: Patrick McHardy <kaber@trash.net>

On Mon, Nov 24, 2008 at 02:48:07PM +0200, Patrick McHardy wrote:
> Wu Fengguang wrote:
> > On Mon, Nov 24, 2008 at 02:23:16PM +0200, Patrick McHardy wrote:
> >> +	/* Avoid bogus warning, gcc doesn't realize do_basic_checks()
> >> +	 * guarantees that there is at least one SCTP chunk.
> >> +	 */
> >> +	if (unlikely(new_state == SCTP_CONNTRACK_MAX))
> >> +		goto out;
> >> +
> > 
> > If do_basic_checks() guarantees that, why not Initialize new_state to 0?
> 
> Good point. I've replaced the patch by this one:

Thanks!

Fengguang

Content-Description: x
> commit 328bd8997dbb7184d5389e45c642af44ae6e9043
> Author: Patrick McHardy <kaber@trash.net>
> Date:   Mon Nov 24 13:44:55 2008 +0100
> 
>     netfilter: nf_conntrack_proto_sctp: avoid bogus warning
>     
>     net/netfilter/nf_conntrack_proto_sctp.c: In function 'sctp_packet':
>     net/netfilter/nf_conntrack_proto_sctp.c:376: warning: array subscript is above array bounds
>     
>     gcc doesn't realize that do_basic_checks() guarantees that there is
>     at least one valid chunk and thus new_state is never SCTP_CONNTRACK_MAX
>     after the loop. Initialize to SCTP_CONNTRACK_NONE to avoid the warning.
>     
>     Based on patch by Wu Fengguang <wfg@linux.intel.com>
>     
>     Signed-off-by: Patrick McHardy <kaber@trash.net>
> 
> diff --git a/net/netfilter/nf_conntrack_proto_sctp.c b/net/netfilter/nf_conntrack_proto_sctp.c
> index c2bd457..74e0379 100644
> --- a/net/netfilter/nf_conntrack_proto_sctp.c
> +++ b/net/netfilter/nf_conntrack_proto_sctp.c
> @@ -317,7 +317,7 @@ static int sctp_packet(struct nf_conn *ct,
>  		goto out;
>  	}
>  
> -	old_state = new_state = SCTP_CONNTRACK_MAX;
> +	old_state = new_state = SCTP_CONNTRACK_NONE;
>  	write_lock_bh(&sctp_lock);
>  	for_each_sctp_chunk (skb, sch, _sch, offset, dataoff, count) {
>  		/* Special cases of Verification tag check (Sec 8.5.1) */

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