Messages in this thread | | | Date | Wed, 31 Oct 2012 16:35:01 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] device_cgroup: fix unchecked cgroup parent usage |
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On Wed, 31 Oct 2012 12:04:30 -0400 Aristeu Rozanski <aris@redhat.com> wrote:
> In 4cef7299b4786879a3e113e84084a72b24590c5b the cgroup parent usage is > unchecked. root will not have a parent and trying to use > device.{allow,deny} will cause problems.
From my reading of the code "problems" means "kernel null pointer dereference".
> For some reason my stressing > scripts didn't test the root directory so I didn't catch it on my > regular tests. > > --- github.orig/security/device_cgroup.c 2012-10-26 17:18:01.739366780 -0400 > +++ github/security/device_cgroup.c 2012-10-29 10:03:33.221918003 -0400 > @@ -352,6 +352,8 @@ > */ > static inline int may_allow_all(struct dev_cgroup *parent)
offtopic: this function could quite neatly have a bool return type.
> { > + if (!parent) > + return 1;
hm. Does it need a comment explaining what and why? I guess not... just.
> return parent->behavior == DEVCG_DEFAULT_ALLOW; > }
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