linux-kernel - [PATCH 3.10 229/250] USB: dummy-hcd: fix bug in stop

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Message-Id: <1496876436-32402-230-git-send-email-w@1wt.eu>
Date:   Thu,  8 Jun 2017 01:00:15 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Alan Stern <stern@...land.harvard.edu>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 229/250] USB: dummy-hcd: fix bug in stop_activity (handle ep0)

From: Alan Stern <stern@...land.harvard.edu>

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 <stern@...land.harvard.edu>
Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Felipe Balbi <felipe.balbi@...ux.intel.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/usb/gadget/dummy_hcd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/dummy_hcd.c b/drivers/usb/gadget/dummy_hcd.c
index ac0e79e..644c105 100644
--- a/drivers/usb/gadget/dummy_hcd.c
+++ b/drivers/usb/gadget/dummy_hcd.c
@@ -266,7 +266,7 @@ 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;
@@ -274,8 +274,8 @@ 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 */
 }
-- 
2.8.0.rc2.1.gbe9624a