ruby-core


>From: Kevin Tew <tewk@tewk.com>
>Date: 07.05.2006 04:49:58
>Subject: Coverity CID 6 7  Appear to be false positives.
>
>CID 6 appears to be a false positive due to the sequence of assignments
>on lines 7015 and 7019
>
>Likewise
>CID 7 appears to be a false positive due to a similar sequence of
>assignments
>on lines 6996 and 7000
>
>If someone with access to Coverity concurs with my analysis could you
>please mark CID 6 and 7 in Coverity accordingly.
>
>Comments and Opinions Welcome

 I think you analysis is correct.  Could you put some comment to these CIDs
 I can the update my analysis to them as well.

For the list:

The Coverity checker  seems to get  confused with linked list handling in
parse.y
006          static NODE*
7007         list_concat(NODE *head, NODE *tail)
7008         {
7009             NODE *last;
7010
                                                                                  
 Event var_compare_op: Added "((head)->u3).node" due to comparison                
 "((head)->u3).node != 0"                                                         
                                                                                  
 Also see events: [var_deref_op][var_deref_op]                                    
                                                                                  
 At conditional (1): "((head)->u3).node != 0" taking false path                   
                                                                                  



The above means that head->nd_next is NULL
7011             if (head->nd_next) {
7012                     last = head->nd_next->nd_end;
7013             }
7014             else {
7015                     last = head;
7016             }
7017
7018             head->nd_alen += tail->nd_alen;
7019             last->nd_next = tail;
                                              
 At conditional (2): "((tail)->u3).node != 0" 
 taking true path                             
                                              



the above means that tail->nd_next is not NULL
7020             if (tail->nd_next) {
                                                                       
 Event var_deref_op: Variable "((head)->u3).node" tracked as NULL was  
 dereferenced.                                                         
                                                                       
 Also see events: [var_compare_op][var_deref_op]                       
                                                                       



here  the checker thinks that head->nd_next is NULL althought it is tail.


7021                     head->nd_next->nd_end = tail->nd_next->nd_end;
7022             }
7023             else {
                                                                       
 Event var_deref_op: Variable "((head)->u3).node" tracked as NULL was  
 dereferenced.                                                         
                                                                       
 Also see events: [var_compare_op][var_deref_op]                       
                                                                       



7024                     head->nd_next->nd_end = tail;
7025             }
7026

>Kevin Tew
>

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