From: Pan Bian <bianpan2016@163.com>
Date: Thu, 7 Nov 2019 09:33:20 +0800
Subject: NFC: st21nfca: fix double free
Git-commit: 99a8efbb6e30b72ac98cecf81103f847abffb1e5
Patch-mainline: 5.4-rc7
References: networking-stable-19_11_10

The variable nfcid_skb is not changed in the callee nfc_hci_get_param()
if error occurs. Consequently, the freed variable nfcid_skb will be
freed again, resulting in a double free bug. Set nfcid_skb to NULL after
releasing it to fix the bug.

Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/nfc/st21nfca/core.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/nfc/st21nfca/core.c
+++ b/drivers/nfc/st21nfca/core.c
@@ -719,6 +719,7 @@ static int st21nfca_hci_complete_target_
 							NFC_PROTO_FELICA_MASK;
 		} else {
 			kfree_skb(nfcid_skb);
+			nfcid_skb = NULL;
 			/* P2P in type A */
 			r = nfc_hci_get_param(hdev, ST21NFCA_RF_READER_F_GATE,
 					ST21NFCA_RF_READER_F_NFCID1,