Subject: Re: [Lksctp-developers] [PATCH] SCTP: Fix kernel panic while received AUTH chunk with BAD shared key identifier

From: Vlad Yasevich <[email-masked]>
Date: Fri, 25 Jan 2008 11:46:39 -0500

Neil Horman wrote:
> On Tue, Jan 22, 2008 at 05:29:20PM +0900, Wei Yongjun wrote:
>>
>> This patch fix this problem.
>>
>> Signed-off-by: Wei Yongjun <[email-masked]>
>>
>> --- a/net/sctp/auth.c	2008-01-21 00:03:25.000000000 -0500
>> +++ b/net/sctp/auth.c	2008-01-21 21:31:47.000000000 -0500
>> @@ -420,15 +420,15 @@ struct sctp_shared_key *sctp_auth_get_sh
>>  				const struct sctp_association *asoc,
>>  				__u16 key_id)
>>  {
>> -	struct sctp_shared_key *key = NULL;
>> +	struct sctp_shared_key *key;
>>  
>>  	/* First search associations set of endpoint pair shared keys */
>>  	key_for_each(key, &asoc->endpoint_shared_keys) {
>>  		if (key->key_id == key_id)
>> -			break;
>> +			return key;
>>  	}
>>  
>> -	return key;
>> +	return NULL;
>>  }
>>  
>>  /*
>>
> 
> FWIW, Ack from me.  The assignment of NULL to key can safely be removed, since
> key_for_each (which is just list_for_each_entry under the covers does an initial
> assignment to key anyway). 
> 
> If the endpoint_shared_keys list is empty, or if the key_id being requested does
> not exist, the function as it currently stands returns the actuall list_head (in
> this case endpoint_shared_keys.  Since that list_head isn't surrounded by an
> actuall data structure, the last iteration through list_for_each_entry will do a
> container_of on key, and we wind up returning a bogus pointer, instead of NULL,
> as we should.  Wei's patch corrects that.
> 
> Regards
> Neil
> 
> Acked-by: Neil Horman <[email-masked]>
> 

Yep, the patch is correct.

Acked-by: Vlad Yasevich <[email-masked]>

-vlad