Rob Weir said:

> Hmm, I'm not really sure.  I've read the discussion on lkml, but a lot of
> it went over my head.  I think the answer is 'yes, for this
> particular one', but the root issue here could also lead to other
> vulnerabilities.  I'm still following that discussion, so I'll post if I
> ever figure it out myself.

at least in the 2.2.x series this is the case. the patch is a 6 line
patch to kernel/kmod.c which is part of CONFIG_KMOD, which cannot be
enabled if modules are disabled. I always have CONFIG_KMOD disabled
anyways since I hate the kernel trying to load things it thinks I want
it to load, so I am not vulnerable.

not sure about 2.4.x I haven't looked at the patch, but I suspect it
is probably the same..

patch for 2.2.x(diff'd against 2.2.19):
--- kernel/kmod.c       Tue Mar 18 14:10:18 2003
+++ kernel/kmod.c       Tue Mar 18 14:11:40 2003
@@ -155,12 +155,18 @@
                atomic_dec(&kmod_concurrent);
                return -ENOMEM;
        }
+       {
+       int old=current->dumpable;
+       current->dumpable=0;    /* block ptrace */

        pid = kernel_thread(exec_modprobe, (void*) module_name, 0);
        if (pid < 0) {
                printk(KERN_ERR "request_module[%s]: fork failed, errno %d\n",
module_name, -pid);
                atomic_dec(&kmod_concurrent);
+               current->dumpable=old;
                return pid;
+       }
+       current->dumpable=old;
        }

        /* Block everything but SIGKILL/SIGSTOP */

nate
(haven't been following the thread been busy playing with my zaurus
for the past few days)



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