linux-kernel - [PATCH] USB: gadget: Fix the memory leak in raw

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Message-Id: <20230714074011.20989-1-qiang.zhang1211@gmail.com>
Date:   Fri, 14 Jul 2023 15:40:11 +0800
From:   Zqiang <qiang.zhang1211@...il.com>
To:     andreyknvl@...il.com, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        qiang.zhang1211@...il.com
Subject: [PATCH] USB: gadget: Fix the memory leak in raw_gadget driver

Currently, increasing raw_dev->count happens before invoke the
raw_queue_event(), if the raw_queue_event() return error, invoke
raw_release() will not trigger the dev_free() to be called.

[  268.905865][ T5067] raw-gadget.0 gadget.0: failed to queue event
[  268.912053][ T5067] udc dummy_udc.0: failed to start USB Raw Gadget: -12
[  268.918885][ T5067] raw-gadget.0: probe of gadget.0 failed with error -12
[  268.925956][ T5067] UDC core: USB Raw Gadget: couldn't find an available UDC or it's busy
[  268.934657][ T5067] misc raw-gadget: fail, usb_gadget_register_driver returned -16

BUG: memory leak

[<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
[<ffffffff8347eb55>] kmalloc include/linux/slab.h:582 [inline]
[<ffffffff8347eb55>] kzalloc include/linux/slab.h:703 [inline]
[<ffffffff8347eb55>] dev_new drivers/usb/gadget/legacy/raw_gadget.c:191 [inline]
[<ffffffff8347eb55>] raw_open+0x45/0x110 drivers/usb/gadget/legacy/raw_gadget.c:385
[<ffffffff827d1d09>] misc_open+0x1a9/0x1f0 drivers/char/misc.c:165

[<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
[<ffffffff8347cd2f>] kmalloc include/linux/slab.h:582 [inline]
[<ffffffff8347cd2f>] raw_ioctl_init+0xdf/0x410 drivers/usb/gadget/legacy/raw_gadget.c:460
[<ffffffff8347dfe9>] raw_ioctl+0x5f9/0x1120 drivers/usb/gadget/legacy/raw_gadget.c:1250
[<ffffffff81685173>] vfs_ioctl fs/ioctl.c:51 [inline]

[<ffffffff8154bf94>] kmalloc_trace+0x24/0x90 mm/slab_common.c:1076
[<ffffffff833ecc6a>] kmalloc include/linux/slab.h:582 [inline]
[<ffffffff833ecc6a>] kzalloc include/linux/slab.h:703 [inline]
[<ffffffff833ecc6a>] dummy_alloc_request+0x5a/0xe0 drivers/usb/gadget/udc/dummy_hcd.c:665
[<ffffffff833e9132>] usb_ep_alloc_request+0x22/0xd0 drivers/usb/gadget/udc/core.c:196
[<ffffffff8347f13d>] gadget_bind+0x6d/0x370 drivers/usb/gadget/legacy/raw_gadget.c:292

This commit therefore invoke kref_get() under the condition that
raw_queue_event() return success.

Reported-by: syzbot+feb045d335c1fdde5bf7@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=feb045d335c1fdde5bf7
Signed-off-by: Zqiang <qiang.zhang1211@...il.com>
---
 drivers/usb/gadget/legacy/raw_gadget.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c
index 2acece16b890..e549022642e5 100644
--- a/drivers/usb/gadget/legacy/raw_gadget.c
+++ b/drivers/usb/gadget/legacy/raw_gadget.c
@@ -310,13 +310,15 @@ static int gadget_bind(struct usb_gadget *gadget,
 	dev->eps_num = i;
 	spin_unlock_irqrestore(&dev->lock, flags);
 
-	/* Matches kref_put() in gadget_unbind(). */
-	kref_get(&dev->count);
-
 	ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
-	if (ret < 0)
+	if (ret < 0) {
 		dev_err(&gadget->dev, "failed to queue event\n");
+		set_gadget_data(gadget, NULL);
+		return ret;
+	}
 
+	/* Matches kref_put() in gadget_unbind(). */
+	kref_get(&dev->count);
 	return ret;
 }
 
-- 
2.17.1