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SubjectRe: [PATCH] drivers: base: core: do not put noninitialized devices
Hi Greg,

On Fri, Nov 19, 2010 at 11:02 -0800, Greg KH wrote:
> On Fri, Nov 19, 2010 at 09:41:40PM +0300, Vasiliy Kulikov wrote:
> > If kobject_set_name_vargs() fails then put_device() frees
> > device with zero kobj->state_initialized. This leads to WARN().
> Have you seen this happen?

No, I've just analized the code. Without device_initialize() ->kobj is
not initialized:

kobject_init(&dev->kobj, &device_ktype) calls

kobject_init_internal(kobj) calls

kobj->state_initialized = 1;

kobject_put() calls WARN if state_initialized == 0:

void kobject_put(struct kobject *kobj)
if (kobj) {
if (!kobj->state_initialized)
WARN(1, KERN_WARNING "kobject: '%s' (%p): is not "
"initialized, yet kobject_put() is being "
"called.\n", kobject_name(kobj), kobj);

I got the stack dump with similar code:

struct device *dev = kzalloc(sizeof(*dev), GFP_KERNEL);

> I'd prefer not to change this unless you are seeing problems with the
> current code.
> How did kobject_set_name_vargs() fail for you?

int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
va_list vargs)
kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
if (!kobj->name)
return -ENOMEM;

char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
p = kmalloc(len+1, gfp);
if (!p)
return NULL;

Unlikely, but may fail in OOM situation.


Vasiliy Kulikov - bringing security into open computing environments

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