netdev - [PATCH] net:nfc:digital: Fix a double free in digital_tg_recv_dep

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Message-Id: <20210427162258.7238-1-lyl2019@mail.ustc.edu.cn>
Date:   Tue, 27 Apr 2021 09:22:58 -0700
From:   Lv Yunlong <lyl2019@...l.ustc.edu.cn>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lv Yunlong <lyl2019@...l.ustc.edu.cn>
Subject: [PATCH] net:nfc:digital: Fix a double free in digital_tg_recv_dep_req

In digital_tg_recv_dep_req, it calls nfc_tm_data_received(..,resp).
If nfc_tm_data_received() failed, the callee will free the resp via
kfree_skb() and return error. But in the exit branch, the resp
will be freed again.

My patch sets resp to NULL if nfc_tm_data_received() failed, to
avoid the double free.

Fixes: 1c7a4c24fbfd9 ("NFC Digital: Add target NFC-DEP support")
Signed-off-by: Lv Yunlong <lyl2019@...l.ustc.edu.cn>
---
 net/nfc/digital_dep.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c
index 5971fb6f51cc..dc21b4141b0a 100644
--- a/net/nfc/digital_dep.c
+++ b/net/nfc/digital_dep.c
@@ -1273,6 +1273,8 @@ static void digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg,
 	}
 
 	rc = nfc_tm_data_received(ddev->nfc_dev, resp);
+	if (rc)
+		resp = NULL;
 
 exit:
 	kfree_skb(ddev->chaining_skb);
-- 
2.25.1