Patch "usb: renesas_usbhs: avoid NULL pointer derefernce in usbhsf_pkt_handler()" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

usb: renesas_usbhs: avoid NULL pointer derefernce in usbhsf_pkt_handler()

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-renesas_usbhs-avoid-null-pointer-derefernce-in-usbhsf_pkt_handler.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Yoshihiro Shimoda <[email protected]>
Date: Thu, 10 Mar 2016 11:30:14 +0900
Subject: usb: renesas_usbhs: avoid NULL pointer derefernce in usbhsf_pkt_handler()

From: Yoshihiro Shimoda <[email protected]>

commit 894f2fc44f2f3f48c36c973b1123f6ab298be160 upstream.

When unexpected situation happened (e.g. tx/rx irq happened while DMAC is used), the usbhsf_pkt_handler() was possible to cause NULL pointer dereference like the followings:

Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 80000007 [#1] SMP ARM
Modules linked in: usb_f_acm u_serial g_serial libcomposite
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.5.0-rc6-00842-gac57066-dirty #63
Hardware name: Generic R8A7790 (Flattened Device Tree)
task: c0729c00 ti: c0724000 task.ti: c0724000
PC is at 0x0
LR is at usbhsf_pkt_handler+0xac/0x118
pc : [<00000000>]    lr : [<c03257e0>]    psr: 60000193

sp : c0725db8 ip : 00000000 fp : c0725df4
r10: 00000001 r9 : 00000193 r8 : ef3ccab4
r7 : ef3cca10 r6 : eea4586c r5 : 00000000 r4 : ef19ceb4 r3 : 00000000 r2 : 0000009c r1 : c0725dc4 r0 : ef19ceb4

This patch adds a condition to avoid the dereference.

---
 drivers/usb/renesas_usbhs/fifo.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -190,7 +190,8 @@ static int usbhsf_pkt_handler(struct usb
 		goto __usbhs_pkt_handler_end;
 	}
 
-	ret = func(pkt, &is_done);
+	if (likely(func))
+		ret = func(pkt, &is_done);
 
 	if (is_done)
 		__usbhsf_pkt_del(pkt);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/usb-renesas_usbhs-fix-to-avoid-using-a-disabled-ep-in-usbhsg_queue_done.patch queue-4.4/usb-renesas_usbhs-avoid-null-pointer-derefernce-in-usbhsf_pkt_handler.patch queue-4.4/usb-renesas_usbhs-disable-tx-irq-before-starting-tx-dmac-transfer.patch