Re: security checkup in source control software

On Fri, 16 Apr 2004 16:34:12 EDT, Jose Nazario said:
> provided you can do arbitrary checks on what was checked in, you can do
> them. just invoke the checking program either on the (positive, stuff
> you're adding) diff or on the resulting source code.

You need to rescan the resulting source code.  There are many failure
modes where the diff itself will be "clean", but the resulting code isn't.

Here's the diff for a contrived example:

*** demo.c.dist 2004-04-16 17:54:23.155185181 -0400
--- demo.c      2004-04-16 17:54:39.340407270 -0400
***************
*** 2,7 ****
--- 2,8 ----
        bindex[i] = rigthptr(i,24);
        if (compare(j,ptr2) > 5) {
                redo_left = 1;
+               lastptr = -1;
                if (compare(j,ptr1) > 7) {
                        redo_right = 1;
                }


Safe?  Looks OK to me, but let's look at more code:

        aindex[i] = leftptr(j,23);
        bindex[i] = rigthptr(i,24);
        if (compare(j,ptr2) > 5) {
                redo_left = 1;
                lastptr = -1;
                if (compare(j,ptr1) > 7) {
                        redo_right = 1;
                }
                rebalance(aindex,bindex,redo_left,redo_right);
        }
        /* Now we do other stuff */
        thinko[lastptr] = sum_value(aindex,bindex);

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