Possible error in kern_sysctl.c

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

In the routine sysctl_create(), when we're adding a new child to an
existing node, we may have to move some existing entries.  If so, we
than have to update the parent pointers of any children whose parent
was moved.  The code to accomplish this is at line 1142

        /*
         * insert new node data
         */
        if (at < pnode->sysctl_clen) {
                int t;

                /*
                 * move the nodes that should come after the new one
                 */
                memmove(&node[at + 1], &node[at],
                        (pnode->sysctl_clen - at) * sizeof(struct sysctlnode));
                memset(&node[at], 0, sizeof(struct sysctlnode));
                node[at].sysctl_parent = pnode;
                /*
                 * and...reparent any children of any moved nodes
                 */
> > >             for (ni = at; ni <= pnode->sysctl_clen; ni++)
                        if (node[ni].sysctl_child != NULL)
                                for (t = 0; t < node[ni].sysctl_csize; t++)
                                        node[ni].sysctl_child[t].sysctl_parent =
                                                &node[ni];
        }


At the tagged >>> line, we start processing at the entry at which we
just inserted the new node, and NOT at the first possibly-moved entry!

If the new entry has a non-NULL sysctl_child pointer we might update
some stuff that shouldn't be touched.  (Note that the new entry's
sysctl_child pointer is not set to NULL until we get to line 1196 in
the same function.)

It seems to me that the for loop on the tagged line should start with
ni = at + 1

This could potentially be the bug I've been tracking where the values
added to a sysctllog contain the wrong mib-name values, preventing
proper operation of sysctl_teardown().


Comments?



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