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

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Message-ID: <000000000000d32294060a922e91@google.com>
Date:   Mon, 20 Nov 2023 01:33:47 -0800
From:   syzbot <syzbot+6eb09d75211863f15e3e@...kaller.appspotmail.com>
To:     linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] Re: [syzbot] [nfc?] memory leak in skb_copy (2)

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***

Subject: Re: [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;