linux-kernel - [PATCH] media: flexcop-usb: fix NULL-ptr deref in flexcop_usb_transfer

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Date:   Tue, 24 Sep 2019 17:49:04 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <mchehab@...nel.org>, <gregkh@...uxfoundation.org>,
        <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] media: flexcop-usb: fix NULL-ptr deref in flexcop_usb_transfer_init()

If usb_set_interface() failed, iface->cur_altsetting will
not be assigned and it will be used in flexcop_usb_transfer_init()
It may lead a NULL pointer dereference.

Check usb_set_interface() return value in flexcop_usb_init()
and return failed to avoid using this NULL pointer.

Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/media/usb/b2c2/flexcop-usb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/b2c2/flexcop-usb.c b/drivers/media/usb/b2c2/flexcop-usb.c
index 1826ff8..4bf85e9 100644
--- a/drivers/media/usb/b2c2/flexcop-usb.c
+++ b/drivers/media/usb/b2c2/flexcop-usb.c
@@ -504,7 +504,13 @@ static int flexcop_usb_transfer_init(struct flexcop_usb *fc_usb)
 static int flexcop_usb_init(struct flexcop_usb *fc_usb)
 {
 	/* use the alternate setting with the larges buffer */
-	usb_set_interface(fc_usb->udev,0,1);
+	int ret = usb_set_interface(fc_usb->udev, 0, 1);
+
+	if (ret) {
+		err("set interface failed.");
+		return ret;
+	}
+
 	switch (fc_usb->udev->speed) {
 	case USB_SPEED_LOW:
 		err("cannot handle USB speed because it is too slow.");
-- 
1.8.3