patch "USB: dummy-hcd: fix bug in stop_activity (handle ep0)" added to usb-linus

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

USB: dummy-hcd: fix bug in stop_activity (handle ep0)

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From: Alan Stern <[email protected]>
Date: Wed, 14 Dec 2016 14:55:56 -0500
Subject: USB: dummy-hcd: fix bug in stop_activity (handle ep0)

The stop_activity() routine in dummy-hcd is supposed to unlink all active requests for every endpoint, among other things. But it doesn't handle ep0. As a result, fuzz testing can generate a WARNING like the following:

WARNING: CPU: 0 PID: 4410 at drivers/usb/gadget/udc/dummy_hcd.c:672 dummy_free_request+0x153/0x170
Modules linked in:
CPU: 0 PID: 4410 Comm: syz-executor Not tainted 4.9.0-rc7+ #32
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffff88006a64ed10 ffffffff81f96b8a ffffffff41b58ab3 1ffff1000d4c9d35
 ffffed000d4c9d2d ffff880065f8ac00 0000000041b58ab3 ffffffff8598b510
 ffffffff81f968f8 0000000041b58ab3 ffffffff859410e0 ffffffff813f0590
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff81f96b8a>] dump_stack+0x292/0x398 lib/dump_stack.c:51
 [<ffffffff812b808f>] __warn+0x19f/0x1e0 kernel/panic.c:550
 [<ffffffff812b831c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff830fcb13>] dummy_free_request+0x153/0x170 drivers/usb/gadget/udc/dummy_hcd.c:672
 [<ffffffff830ed1b0>] usb_ep_free_request+0xc0/0x420 drivers/usb/gadget/udc/core.c:195
 [<ffffffff83225031>] gadgetfs_unbind+0x131/0x190 drivers/usb/gadget/legacy/inode.c:1612
 [<ffffffff830ebd8f>] usb_gadget_remove_driver+0x10f/0x2b0 drivers/usb/gadget/udc/core.c:1228
 [<ffffffff830ec084>] usb_gadget_unregister_driver+0x154/0x240 drivers/usb/gadget/udc/core.c:1357

This patch fixes the problem by iterating over all the endpoints in the driver's ep array instead of iterating over the gadget's ep_list, which explicitly leaves out ep0.

---
 drivers/usb/gadget/udc/dummy_hcd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 02b14e91ae6c..c60abe3a68f9 100644
@@ -330,7 +330,7 @@ static void nuke(struct dummy *dum, struct dummy_ep *ep)
 /* caller must hold lock */
 static void stop_activity(struct dummy *dum)
 {
-	struct dummy_ep	*ep;
+	int i;
 
 	/* prevent any more requests */
 	dum->address = 0;

@@ -338,8 +338,8 @@ static void stop_activity(struct dummy *dum)
 	/* The timer is left running so that outstanding URBs can fail */
 
 	/* nuke any pending requests first, so driver i/o is quiesced */
-	list_for_each_entry(ep, &dum->gadget.ep_list, ep.ep_list)
-		nuke(dum, ep);
+	for (i = 0; i < DUMMY_ENDPOINTS; ++i)
+		nuke(dum, &dum->ep[i]);
 
 	/* driver now does any non-usb quiescing necessary */
 }

2.11.0