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Subject[PATCH 3.2 060/199] USB: dummy-hcd: fix bug in stop_activity (handle ep0)
3.2.87-rc1 review patch.  If anyone has any objections, please let me know.


From: Alan Stern <>

commit bcdbeb844773333d2d1c08004f3b3e25921040e5 upstream.

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.

Signed-off-by: Alan Stern <>
Reported-by: Andrey Konovalov <>
Signed-off-by: Felipe Balbi <>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <>
drivers/usb/gadget/dummy_hcd.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -261,7 +261,7 @@ static void nuke (struct dummy *dum, str
static void
stop_activity (struct dummy *dum)
- struct dummy_ep *ep;
+ int i;

/* prevent any more requests */
dum->address = 0;
@@ -269,8 +269,8 @@ 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 */
 \ /
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