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From:   Nguyen Dinh Phi <phind.uet@gmail.com>
To:     bongsu.jeon@samsung.com, krzysztof.kozlowski@linaro.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Nguyen Dinh Phi <phind.uet@gmail.com>,
        syzbot+6eb09d75211863f15e3e@syzkaller.appspotmail.com
Subject: [PATCH] nfc: virtual_ncidev: Add variable to check if ndev is running
Date:   Mon, 20 Nov 2023 00:47:05 +0800
Message-Id: <20231119164705.1991375-1-phind.uet@gmail.com>
MIME-Version: 1.0
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syzbot reported an memory leak that happens when an skb is add to
send_buff after virtual nci closed.
This patch adds a variable to track if the ndev is running before
handling new skb in send function.

Reported-by: syzbot+6eb09d75211863f15e3e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/lkml/00000000000075472b06007df4fb@google.com
Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
---
 drivers/nfc/virtual_ncidev.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nfc/virtual_ncidev.c b/drivers/nfc/virtual_ncidev.c
index b027be0b0b6f..ac8226db54e2 100644
--- a/drivers/nfc/virtual_ncidev.c
+++ b/drivers/nfc/virtual_ncidev.c
@@ -20,26 +20,31 @@
 				 NFC_PROTO_ISO14443_MASK | \
 				 NFC_PROTO_ISO14443_B_MASK | \
 				 NFC_PROTO_ISO15693_MASK)
+#define NCIDEV_RUNNING 0
 
 struct virtual_nci_dev {
 	struct nci_dev *ndev;
 	struct mutex mtx;
 	struct sk_buff *send_buff;
 	struct wait_queue_head wq;
+	bool running;
 };
 
 static int virtual_nci_open(struct nci_dev *ndev)
 {
+	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
+
+	vdev->running = true;
 	return 0;
 }
 
 static int virtual_nci_close(struct nci_dev *ndev)
 {
 	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
-
 	mutex_lock(&vdev->mtx);
 	kfree_skb(vdev->send_buff);
 	vdev->send_buff = NULL;
+	vdev->running = false;
 	mutex_unlock(&vdev->mtx);
 
 	return 0;
@@ -50,7 +55,7 @@ static int virtual_nci_send(struct nci_dev *ndev, struct sk_buff *skb)
 	struct virtual_nci_dev *vdev = nci_get_drvdata(ndev);
 
 	mutex_lock(&vdev->mtx);
-	if (vdev->send_buff) {
+	if (vdev->send_buff || !vdev->running) {
 		mutex_unlock(&vdev->mtx);
 		kfree_skb(skb);
 		return -1;
-- 
2.34.1