usb: dwc3: gadget: fix NULL pointer dereference in dwc3_wIndex_to_dep

This patch fixes the kernel panic issue when do reboot test
on RV1126 USB AI Camera Board with the following error log:

[3.818529] android_work: did not send uevent (0 0   (null))
[3.890319] android_work: sent uevent USB_STATE=CONNECTED
[3.929523] configfs-gadget gadget: high-speed config #1: b
[3.929743] configfs-gadget gadget: uvc_function_set_alt(2, 0)
[3.929771] configfs-gadget gadget: reset UVC Control
[3.929806] configfs-gadget gadget: uvc_function_set_alt(3, 0)
[3.930243] android_work: sent uevent USB_STATE=CONFIGURED
[3.931423] dwc3 ffd00000.dwc3: unexpected direction for Data Phase
[3.931543] Unable to handle kernel NULL pointer dereference at virtual address 0000005c
[3.933344] pgd = 6319bbbb
[3.933600] [0000005c] *pgd=00000000
[3.933941] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
[3.934433] Modules linked in: galcore(O)
[3.934832] CPU: 0 PID: 568 Comm: irq/61-dwc3 Tainted: G           O      4.19.111 #9
[3.935523] Hardware name: Generic DT based system
[3.935974] PC is at dwc3_ep0_interrupt+0x638/0x80c
[3.936417] LR is at dwc3_thread_interrupt+0x7d4/0xbfc
[3.936897] pc : [<b0521224>]    lr : [<b051ea4c>]    psr: 600d00d3
[3.937462] sp : e607fe88  ip : 00000003  fp : e837d040
[3.937925] r10: e830e640  r9 : 00000008  r8 : e8302900
[3.938386] r7 : 00000000  r6 : e607ff08  r5 : e837d040  r4 : b0c08c48
[3.938965] r3 : 00000050  r2 : 00000000  r1 : e9042000  r0 : 00000004
[3.939546] Flags: nZCv  IRQs off  FIQs off  Mode SVC_32  ISA ARM  Segment user
[3.940213] Control: 10c5387d  Table: 3671c06a  DAC: 00000055
...
[4.013246] [<b0521224>] (dwc3_ep0_interrupt) from [<b051ea4c>] (dwc3_thread_interrupt+0x7d4/0xbfc)
[4.014059] [<b051ea4c>] (dwc3_thread_interrupt) from [<b016ded0>] (irq_thread_fn+0x1c/0x7c)
[4.014835] [<b016ded0>] (irq_thread_fn) from [<b016e1d4>] (irq_thread+0x124/0x200)
[4.015520] [<b016e1d4>] (irq_thread) from [<b014290c>] (kthread+0x140/0x170)
[4.016175] [<b014290c>] (kthread) from [<b01010d8>] (ret_from_fork+0x14/0x3c)
[4.016831] Exception stack(0xe607ffb0 to 0xe607fff8)

Change-Id: I4191444b527eb03a5283f662b1ad4c9d9c08cd19
Signed-off-by: William Wu <[email protected]>

Author: wuliangfeng

drivers/usb/dwc3/ep0.c

@@ -292,6 +292,11 @@ static struct dwc3_ep *dwc3_wIndex_to_dep(struct dwc3 *dwc, __le16 wIndex_le)
 		epnum |= 1;
 
 	dep = dwc->eps[epnum];
+	if (!dep) {
+		dev_warn(dwc->dev, "epnum %d, windex 0x%08x\n", epnum, windex);
+		return NULL;
+	}
+
 	if (dep->flags & DWC3_EP_ENABLED)
 		return dep;