Messages in this thread | | | Date | Sun, 20 Jun 2021 11:53:18 +0800 | From | linyyuan@codeauro ... | Subject | Re: [PATCH v3 1/2] usb: udc: core: hide struct usb_gadget_driver to gadget driver |
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On 2021-06-20 11:46, linyyuan@codeaurora.org wrote: > On 2021-06-20 10:13, Alan Stern wrote: >> On Sat, Jun 19, 2021 at 11:43:08PM +0800, Linyu Yuan wrote: >>> currently most gadget driver have a pointer to save >>> struct usb_gadget_driver from upper layer, >>> it allow upper layer set and unset of the pointer. >>> >>> there is race that upper layer unset the pointer first, >>> but gadget driver use the pointer later, >>> and it cause system crash due to NULL pointer access. >> >> This race has already been fixed in Greg's usb-next branch. See >> commit >> 7dc0c55e9f30 ("USB: UDC core: Add udc_async_callbacks gadget op") and >> following commits 04145a03db9d ("USB: UDC: Implement >> udc_async_callbacks in dummy-hcd") and b42e8090ba93 ("USB: UDC: >> Implement udc_async_callbacks in net2280"). >> > thanks, this is better, lower driver only need change several places. >> You just need to write a corresponding patch implementing the >> async_callbacks op for dwc3. > yes, i will do. >> Alan, i want to discuss your suggestion again in b42e8090ba93 ("USB: UDC: Implement udc_async_callbacks in net2280")
+ if (dev->async_callbacks) { ----> if CPU1 saw this is true + spin_unlock(&dev->lock); ---> CPU2 get lock after this unlock, it will set async_callbacks to false, then follow call also crash, right ? + tmp = dev->driver->setup(&dev->gadget, &u.r); + spin_lock(&dev->lock); + }
>> Alan Stern
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