[kbuild] drivers/usb/gadget/udc/fsl_udc_core.c:1055 fsl_ep_fifo_status() error: we previously assumed '_ep->desc' could be null (see line 1055)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   625d3449788f85569096780592549d0340e9c0c7
commit: 75eaa498c99eebf9f9237656f69469e50197cc0b usb: gadget: Correct NULL pointer checking in fsl gadget
config: arm64-randconfig-m031-20200622 (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

New smatch warnings:
drivers/usb/gadget/udc/fsl_udc_core.c:1055 fsl_ep_fifo_status() error: we previously assumed '_ep->desc' could be null (see line 1055)

# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=75eaa498c99eebf9f9237656f69469e50197cc0b
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git remote update linus
git checkout 75eaa498c99eebf9f9237656f69469e50197cc0b
vim +1055 drivers/usb/gadget/udc/fsl_udc_core.c

2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1047  static int fsl_ep_fifo_status(struct usb_ep *_ep)
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1048  {
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1049  	struct fsl_ep *ep;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1050  	struct fsl_udc *udc;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1051  	int size = 0;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1052  	u32 bitmask;
6414e94c203d92 drivers/usb/gadget/fsl_udc_core.c     Li Yang            2011-11-23  1053  	struct ep_queue_head *qh;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1054  
75eaa498c99eeb drivers/usb/gadget/udc/fsl_udc_core.c Nikhil Badola      2019-10-21 @1055  	if (!_ep || _ep->desc || !(_ep->desc->bEndpointAddress&0xF))
                                                                                                            ^^^^^^^^^
Reversed NULL test.  This will always return -ENODEV.  (Or possibly
crash.  But I suspect it always returns -ENODEV instead of crashing).

The container_of() macro doesn't dereference anything, btw.  It just
does pointer math.  I think it would be cleaner to use ep_index() like
the original code did.  In other words, perhaps it would look best
written like this:

	ep = container_of(_ep, struct fsl_ep, ep);
	if (!_ep || !_ep->desc || ep_index(ep) == 0)


2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1056  		return -ENODEV;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1057  
75eaa498c99eeb drivers/usb/gadget/udc/fsl_udc_core.c Nikhil Badola      2019-10-21  1058  	ep = container_of(_ep, struct fsl_ep, ep);
75eaa498c99eeb drivers/usb/gadget/udc/fsl_udc_core.c Nikhil Badola      2019-10-21  1059  
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1060  	udc = (struct fsl_udc *)ep->udc;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1061  
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1062  	if (!udc->driver || udc->gadget.speed == USB_SPEED_UNKNOWN)
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1063  		return -ESHUTDOWN;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1064  
6414e94c203d92 drivers/usb/gadget/fsl_udc_core.c     Li Yang            2011-11-23  1065  	qh = get_qh_by_ep(ep);
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1066  
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1067  	bitmask = (ep_is_in(ep)) ? (1 << (ep_index(ep) + 16)) :
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1068  	    (1 << (ep_index(ep)));
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1069  
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1070  	if (fsl_readl(&dr_regs->endptstatus) & bitmask)
6414e94c203d92 drivers/usb/gadget/fsl_udc_core.c     Li Yang            2011-11-23  1071  		size = (qh->size_ioc_int_sts & DTD_PACKET_SIZE)
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1072  		    >> DTD_LENGTH_BIT_POS;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1073  
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1074  	pr_debug("%s %u\n", __func__, size);
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1075  	return size;
2ea6698d7b9266 drivers/usb/gadget/fsl_udc_core.c     Anatolij Gustschin 2011-04-18  1076  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip

_______________________________________________
kbuild mailing list -- kbuild@xxxxxxxxxxxx
To unsubscribe send an email to kbuild-leave@xxxxxxxxxxxx