linux-kernel - Re: [syzbot] Private message regarding: [syzbot] [nfc?] memory leak in skb

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Message-ID: <0000000000007eb04f060a91ffad@google.com>
Date:   Mon, 20 Nov 2023 01:20:33 -0800
From:   syzbot <syzbot+6eb09d75211863f15e3e@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] Private message regarding: [syzbot] [nfc?] memory leak
 in skb_copy (2)

For archival purposes, forwarding an incoming command email to
linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com.

***

Subject: Private message regarding: [syzbot] [nfc?] memory leak in skb_copy (2)
Author: phind.uet@...il.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
 master
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;