Re: [usb_add_gadget_udc_release] BUG: KASAN: double-free or invalid-free in (null)

[Felipe Balbi]

Hi,

Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> On Sun, 17 Dec 2017, Fengguang Wu wrote:
>
>> Hello,
>> 
>> FYI this happens in mainline kernel 4.15.0-rc3.
>> It looks like a new regression.
>> 
>> It occurs in 23 out of 36 boots.
>> 
>> [   38.592360] LUN: removable file: (no medium)
>> [   38.593442] no file given for LUN0
>> [   38.594589] g_mass_storage usbip-vudc.0: failed to start g_mass_storage: -22
>> [   38.600881] udc usbip-vudc.0: releasing 'usbip-vudc.0'
>> [   38.604397] ==================================================================
>> [   38.605034] BUG: KASAN: double-free or invalid-free in           (null)
>> [   38.605034]
>> [   38.605034] CPU: 0 PID: 1 Comm: swapper Not tainted 4.15.0-rc3 #468
>> [   38.605034] Call Trace:
>> [   38.605034]  dump_stack+0x2f/0x3e:
>> 						__dump_stack at lib/dump_stack.c:17
>> 						 (inlined by) dump_stack at lib/dump_stack.c:63
>> [   38.605034]  print_address_description+0xc2/0x3b7:
>> 						print_address_description at mm/kasan/report.c:253
>> [   38.605034]  kasan_report_double_free+0x50/0x8c:
>> 						kasan_report_double_free at mm/kasan/report.c:334
>> [   38.605034]  kasan_slab_free+0x60/0x1ef:
>> 						kasan_slab_free at mm/kasan/kasan.c:514
>> [   38.605034]  ? ftrace_likely_update+0x5c/0xc4:
>> 						ftrace_likely_update at kernel/trace/trace_branch.c:223
>> [   38.605034]  ? kobj_kset_leave+0x193/0x1dc:
>> 						kobj_kset_leave at lib/kobject.c:184
>> [   38.605034]  ? lock_acquired+0x8d2/0x8d2:
>> 						lock_release at kernel/locking/lockdep.c:4013
>> [   38.605034]  ? ftrace_likely_update+0x5c/0xc4:
>> 						ftrace_likely_update at kernel/trace/trace_branch.c:223
>> [   38.605034]  ? trace_preempt_on+0x489/0x4d7:
>> 						trace_preempt_enable_rcuidle at include/trace/events/preemptirq.h:50
>> 						 (inlined by) trace_preempt_on at kernel/trace/trace_irqsoff.c:855
>> [   38.605034]  ? static_obj+0x40/0x40:
>> 						match_held_lock at kernel/locking/lockdep.c:3567
>> [   38.605034]  ? kobject_put+0xf5/0x642:
>> 						refcount_dec_and_test at arch/x86/include/asm/refcount.h:75
>> 						 (inlined by) kref_put at include/linux/kref.h:69
>> 						 (inlined by) kobject_put at lib/kobject.c:694
>> [   38.605034]  ? trace_hardirqs_off+0x17/0x1f:
>> 						trace_hardirqs_off at kernel/locking/lockdep.c:2984
>> [   38.605034]  ? kfree+0x419/0x5e7:
>> 						slab_free_hook at mm/slub.c:1380
>> 						 (inlined by) slab_free_freelist_hook at mm/slub.c:1412
>> 						 (inlined by) slab_free at mm/slub.c:2968
>> 						 (inlined by) kfree at mm/slub.c:3899
>> [   38.605034]  kfree+0x43c/0x5e7:
>> 						slab_free at mm/slub.c:2973
>> 						 (inlined by) kfree at mm/slub.c:3899
>> [   38.605034]  usb_add_gadget_udc_release+0x693/0x6ca:
>> 						usb_add_gadget_udc_release at drivers/usb/gadget/udc/core.c:1199
>
> Boy, the error handling in that routine is a mess.  The patch below 
> should straighten it out.

looks good:

Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>


> Alan Stern
>
>
>
> Index: usb-4.x/drivers/usb/gadget/udc/core.c
> ===================================================================
> --- usb-4.x.orig/drivers/usb/gadget/udc/core.c
> +++ usb-4.x/drivers/usb/gadget/udc/core.c
> @@ -1147,11 +1147,7 @@ int usb_add_gadget_udc_release(struct de
>  
>  	udc = kzalloc(sizeof(*udc), GFP_KERNEL);
>  	if (!udc)
> -		goto err1;
> -
> -	ret = device_add(&gadget->dev);
> -	if (ret)
> -		goto err2;
> +		goto err_put_gadget;
>  
>  	device_initialize(&udc->dev);
>  	udc->dev.release = usb_udc_release;
> @@ -1160,7 +1156,11 @@ int usb_add_gadget_udc_release(struct de
>  	udc->dev.parent = parent;
>  	ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
>  	if (ret)
> -		goto err3;
> +		goto err_put_udc;
> +
> +	ret = device_add(&gadget->dev);
> +	if (ret)
> +		goto err_put_udc;
>  
>  	udc->gadget = gadget;
>  	gadget->udc = udc;
> @@ -1170,7 +1170,7 @@ int usb_add_gadget_udc_release(struct de
>  
>  	ret = device_add(&udc->dev);
>  	if (ret)
> -		goto err4;
> +		goto err_unlist_udc;
>  
>  	usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
>  	udc->vbus = true;
> @@ -1178,27 +1178,25 @@ int usb_add_gadget_udc_release(struct de
>  	/* pick up one of pending gadget drivers */
>  	ret = check_pending_gadget_drivers(udc);
>  	if (ret)
> -		goto err5;
> +		goto err_del_udc;
>  
>  	mutex_unlock(&udc_lock);
>  
>  	return 0;
>  
> -err5:
> + err_del_udc:
>  	device_del(&udc->dev);
>  
> -err4:
> + err_unlist_udc:
>  	list_del(&udc->list);
>  	mutex_unlock(&udc_lock);
>  
> -err3:
> -	put_device(&udc->dev);
>  	device_del(&gadget->dev);
>  
> -err2:
> -	kfree(udc);
> + err_put_udc:
> +	put_device(&udc->dev);
>  
> -err1:
> + err_put_gadget:
>  	put_device(&gadget->dev);
>  	return ret;
>  }
>
> --
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-- 
balbi