[PATCH] usb: gadget: f_fs: Fix unbalanced spinlock in __ffs_ep0_queue_wait

From: Udipto Goswami <quic_ugoswami@quicinc.com>
To: John Keeping <john@metanate.com>,
	Dan Carpenter <error27@gmail.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	<linux-usb@vger.kernel.org>
Cc: Pratham Pratap <quic_ppratap@quicinc.com>,
	Udipto Goswami <quic_ugoswami@quicinc.com>
Subject: [PATCH] usb: gadget: f_fs: Fix unbalanced spinlock in  __ffs_ep0_queue_wait
Date: Tue, 24 Jan 2023 14:41:49 +0530	[thread overview]
Message-ID: <20230124091149.18647-1-quic_ugoswami@quicinc.com> (raw)

__ffs_ep0_queue_wait executes holding the spinlock of &ffs->ev.waitq.lock
and unlocks it after the assignments to usb_request are done.
However in the code if the request is already NULL we bail out returning
-EINVAL but never unlocked the spinlock.

Fix this by adding spin_unlock_irq &ffs->ev.waitq.lock before returning.

Fixes: 6a19da111057("usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait")
Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
---
 drivers/usb/gadget/function/f_fs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 523a961b910b..8ad354741380 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -279,8 +279,10 @@ static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
 	struct usb_request *req = ffs->ep0req;
 	int ret;
 
-	if (!req)
+	if (!req) {
+		spin_unlock_irq(&ffs->ev.waitq.lock);
 		return -EINVAL;
+	}
 
 	req->zero     = len < le16_to_cpu(ffs->ev.setup.wLength);
 
-- 
2.17.1

