This is a patch to fix a local root exploit revealed in
early February 2008.  To apply it to the 2.6.21.5 kernel,
do this:

cd /usr/src/linux-2.6.21.5
zcat splice.c.gz | patch -p1

You'll then be ready to build patched kernels from the
config files in the k/ directory.  Copy the config file 
to /usr/src/linux-2.6.21.5/.config, run "make oldconfig", 
run "make vmlinux"

Then build the Slackware kernel package like this:
./kernel-generic.SlackBuild

Don't forget to run ybin again.