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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Yang Yingliang <yangyingliang@huawei.com>,
        Sean Young <sean@mess.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 024/171] media: flexcop-usb: fix NULL-ptr deref in flexcop_usb_transfer_init()
Date:   Thu,  2 Jan 2020 23:05:55 +0100
Message-Id: <20200102220550.463413694@linuxfoundation.org>
In-Reply-To: <20200102220546.960200039@linuxfoundation.org>
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From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 649cd16c438f51d4cd777e71ca1f47f6e0c5e65d ]

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@huawei.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 1fc3c8d7dd9b..2594d6a7393f 100644
--- a/drivers/media/usb/b2c2/flexcop-usb.c
+++ b/drivers/media/usb/b2c2/flexcop-usb.c
@@ -504,7 +504,13 @@ urb_error:
 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.");
-- 
2.20.1