netdev - [PATCH v2] bluetooth/rfcomm: fix ODEBUG bug in rfcomm_dev

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Message-Id: <1583660727-9227-1-git-send-email-hqjagain@gmail.com>
Date:   Sun,  8 Mar 2020 17:45:27 +0800
From:   Qiujun Huang <hqjagain@...il.com>
To:     marcel@...tmann.org
Cc:     johan.hedberg@...il.com, davem@...emloft.net, kuba@...nel.org,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, hdanton@...a.com,
        Qiujun Huang <hqjagain@...il.com>
Subject: [PATCH v2] bluetooth/rfcomm: fix ODEBUG bug in rfcomm_dev_ioctl

Needn't call 'rfcomm_dlc_put' here, because 'rfcomm_dlc_exists' didn't
increase dlc->refcnt.

Reported-by: syzbot+4496e82090657320efc6@...kaller.appspotmail.com
Signed-off-by: Qiujun Huang <hqjagain@...il.com>
Suggested-by: Hillf Danton <hdanton@...a.com>
---
 net/bluetooth/rfcomm/tty.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index 0c7d31c..a585849 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -413,10 +413,8 @@ static int __rfcomm_create_dev(struct sock *sk, void __user *arg)
 		dlc = rfcomm_dlc_exists(&req.src, &req.dst, req.channel);
 		if (IS_ERR(dlc))
 			return PTR_ERR(dlc);
-		else if (dlc) {
-			rfcomm_dlc_put(dlc);
+		if (dlc)
 			return -EBUSY;
-		}
 		dlc = rfcomm_dlc_alloc(GFP_KERNEL);
 		if (!dlc)
 			return -ENOMEM;
-- 
1.8.3.1