mremap vulnerability patch for WOLK

Hi,

you can fix up WOLK (most kernels, in fact) with regard to the security flaw described by CAN-2003-0985 by using the patch below. Note that this is the "proper" patch approved by Linus, not the deprecated one which unfortunately made it into the official 2.4.24 release.

--- linux/mm/mremap.c.orig      2004-01-05 17:01:21.382104120 +0000
+++ linux/mm/mremap.c   2004-01-05 17:15:25.689749848 +0000
@@ -315,6 +315,10 @@
        old_len = PAGE_ALIGN(old_len);
        new_len = PAGE_ALIGN(new_len);
 
+       /* Don't allow the degenerate cases */
+       if (!(old_len | new_len))
+               goto out;
+
        /* new_addr is only valid if MREMAP_FIXED is specified */
        if (flags & MREMAP_FIXED) {
                if (new_addr & ~PAGE_MASK)

--Kerin Millar


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