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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, Pan Bian <bianpan2016@163.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.9 07/65] NFC: st21nfca: fix double free
Date:   Mon, 11 Nov 2019 19:28:07 +0100
Message-Id: <20191111181336.300618727@linuxfoundation.org>
In-Reply-To: <20191111181331.917659011@linuxfoundation.org>
References: <20191111181331.917659011@linuxfoundation.org>
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From: Pan Bian <bianpan2016@163.com>

[ Upstream commit 99a8efbb6e30b72ac98cecf81103f847abffb1e5 ]

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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,