drivers/usb/core/devio.c:1155 do_proc_control() error: copy_from_user() 'tbuf' too small (4096 vs 8192)

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   049eb096da48db0421dd5e358b9b082a1a8a2025
commit: c17536d0abde2fd24afca542e3bb73b45a299633 usb: usbfs: stop using compat_alloc_user_space
date:   2 weeks ago
config: nds32-randconfig-m031-20200808 (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0

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

smatch warnings:
drivers/usb/core/devio.c:1155 do_proc_control() error: copy_from_user() 'tbuf' too small (4096 vs 8192)

vim +/tbuf +1155 drivers/usb/core/devio.c

  1104	
  1105	static int do_proc_control(struct usb_dev_state *ps,
  1106			struct usbdevfs_ctrltransfer *ctrl)
  1107	{
  1108		struct usb_device *dev = ps->dev;
  1109		unsigned int tmo;
  1110		unsigned char *tbuf;
  1111		unsigned wLength;
  1112		int i, pipe, ret;
  1113	
  1114		ret = check_ctrlrecip(ps, ctrl->bRequestType, ctrl->bRequest,
  1115				      ctrl->wIndex);
  1116		if (ret)
  1117			return ret;
  1118		wLength = ctrl->wLength;	/* To suppress 64k PAGE_SIZE warning */
  1119		if (wLength > PAGE_SIZE)
  1120			return -EINVAL;
  1121		ret = usbfs_increase_memory_usage(PAGE_SIZE + sizeof(struct urb) +
  1122				sizeof(struct usb_ctrlrequest));
  1123		if (ret)
  1124			return ret;
  1125		tbuf = (unsigned char *)__get_free_page(GFP_KERNEL);
  1126		if (!tbuf) {
  1127			ret = -ENOMEM;
  1128			goto done;
  1129		}
  1130		tmo = ctrl->timeout;
  1131		snoop(&dev->dev, "control urb: bRequestType=%02x "
  1132			"bRequest=%02x wValue=%04x "
  1133			"wIndex=%04x wLength=%04x\n",
  1134			ctrl->bRequestType, ctrl->bRequest, ctrl->wValue,
  1135			ctrl->wIndex, ctrl->wLength);
  1136		if (ctrl->bRequestType & 0x80) {
  1137			pipe = usb_rcvctrlpipe(dev, 0);
  1138			snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT, NULL, 0);
  1139	
  1140			usb_unlock_device(dev);
  1141			i = usb_control_msg(dev, pipe, ctrl->bRequest,
  1142					    ctrl->bRequestType, ctrl->wValue, ctrl->wIndex,
  1143					    tbuf, ctrl->wLength, tmo);
  1144			usb_lock_device(dev);
  1145			snoop_urb(dev, NULL, pipe, max(i, 0), min(i, 0), COMPLETE,
  1146				  tbuf, max(i, 0));
  1147			if ((i > 0) && ctrl->wLength) {
  1148				if (copy_to_user(ctrl->data, tbuf, i)) {
  1149					ret = -EFAULT;
  1150					goto done;
  1151				}
  1152			}
  1153		} else {
  1154			if (ctrl->wLength) {
> 1155				if (copy_from_user(tbuf, ctrl->data, ctrl->wLength)) {
  1156					ret = -EFAULT;
  1157					goto done;
  1158				}
  1159			}
  1160			pipe = usb_sndctrlpipe(dev, 0);
  1161			snoop_urb(dev, NULL, pipe, ctrl->wLength, tmo, SUBMIT,
  1162				tbuf, ctrl->wLength);
  1163	
  1164			usb_unlock_device(dev);
  1165			i = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), ctrl->bRequest,
  1166					    ctrl->bRequestType, ctrl->wValue, ctrl->wIndex,
  1167					    tbuf, ctrl->wLength, tmo);
  1168			usb_lock_device(dev);
  1169			snoop_urb(dev, NULL, pipe, max(i, 0), min(i, 0), COMPLETE, NULL, 0);
  1170		}
  1171		if (i < 0 && i != -EPIPE) {
  1172			dev_printk(KERN_DEBUG, &dev->dev, "usbfs: USBDEVFS_CONTROL "
  1173				   "failed cmd %s rqt %u rq %u len %u ret %d\n",
  1174				   current->comm, ctrl->bRequestType, ctrl->bRequest,
  1175				   ctrl->wLength, i);
  1176		}
  1177		ret = i;
  1178	 done:
  1179		free_page((unsigned long) tbuf);
  1180		usbfs_decrease_memory_usage(PAGE_SIZE + sizeof(struct urb) +
  1181				sizeof(struct usb_ctrlrequest));
  1182		return ret;
  1183	}
  1184	

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