Messages in this thread |  | | From | Dmitry Torokhov <> | Date | Mon, 20 Aug 2018 12:33:50 -0700 | Subject | Re: [PATCH] kobject: Access kobject name with caution if state is not initialized |
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On Mon, Aug 20, 2018 at 12:22 PM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Mon, Aug 20, 2018 at 10:39:47PM +0530, Srikar Dronamraju wrote: > > If kobject state is not initialized, then its not even certain that > > kobject'name is initialized. Hence when accessing the kobject's name > > tread carefully. > > > > A stupid module test like > > https://github.com/srikard/tests/blob/master/modules/kobject_test.c > > can panic the system. > > Lots of stupid modules can do dumb things. Just don't do that. The > kernel is not built to keep you from doing stupid things in kernel code > :) > > So I fail to see why this patch is needed. What in-kernel code path is > trying to print a kobject's name before it is initialized? Why not fix > that obvious bug instead of forcing the kernel core to protect from > stupid code?
Kay decided to add some guards in:
commit 0f4dafc0563c6c49e17fe14b3f5f356e4c4b8806 Author: Kay Sievers <kay.sievers@vrfy.org> Date: Wed Dec 19 01:40:42 2007 +0100
Kobject: auto-cleanup on final unref ...
+ if (!kobj->state_initialized) { + printk(KERN_ERR "kobject '%s' (%p): tried to add an " + "uninitialized object, something is seriously wrong.\n", + kobject_name(kobj), kobj); + dump_stack(); + return -EINVAL;
Given that we have dump_stack() we can probably simply drop kobject_name(kobj) instead of building even more elaborate checks. Or just drop the whole check. Adding kobjects is somewhat uncommon operation, plus "gabage in, garbage out".
Thanks.
-- Dmitry
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