linux-kernel - [PATCH] NFC: netlink: remove unexpected nfc_put

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Message-Id: <1543305275-23051-1-git-send-email-bianpan2016@163.com>
Date:   Tue, 27 Nov 2018 15:54:35 +0800
From:   Pan Bian <bianpan2016@....com>
To:     Samuel Ortiz <sameo@...ux.intel.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Pan Bian <bianpan2016@....com>
Subject: [PATCH] NFC: netlink: remove unexpected nfc_put_device

The functions nfc_genl_llc_set_params and nfc_genl_llc_sdreq drops the
reference to dev via nfc_put_device on the error branch that no local
device is found. However, the error handling block reads dev's field and
then put dev again. This may result in use-after-free bugs. The patch
removes the unexpected call to nfc_put_device.

Signed-off-by: Pan Bian <bianpan2016@....com>
---
 net/nfc/netlink.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
index 376181c..e1f2057 100644
--- a/net/nfc/netlink.c
+++ b/net/nfc/netlink.c
@@ -1107,7 +1107,6 @@ static int nfc_genl_llc_set_params(struct sk_buff *skb, struct genl_info *info)
 
 	local = nfc_llcp_find_local(dev);
 	if (!local) {
-		nfc_put_device(dev);
 		rc = -ENODEV;
 		goto exit;
 	}
@@ -1167,7 +1166,6 @@ static int nfc_genl_llc_sdreq(struct sk_buff *skb, struct genl_info *info)
 
 	local = nfc_llcp_find_local(dev);
 	if (!local) {
-		nfc_put_device(dev);
 		rc = -ENODEV;
 		goto exit;
 	}
-- 
2.7.4