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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, Pavel Skripkin <paskripkin@gmail.com>,
        Marcel Holtmann <marcel@holtmann.org>,
        Sasha Levin <sashal@kernel.org>,
        syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com
Subject: [PATCH 5.4 100/144] Bluetooth: add timeout sanity check to hci_inquiry
Date:   Mon, 13 Sep 2021 15:14:41 +0200
Message-Id: <20210913131051.284199891@linuxfoundation.org>
In-Reply-To: <20210913131047.974309396@linuxfoundation.org>
References: <20210913131047.974309396@linuxfoundation.org>
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From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit f41a4b2b5eb7872109723dab8ae1603bdd9d9ec1 ]

Syzbot hit "task hung" bug in hci_req_sync(). The problem was in
unreasonable huge inquiry timeout passed from userspace.
Fix it by adding sanity check for timeout value to hci_inquiry().

Since hci_inquiry() is the only user of hci_req_sync() with user
controlled timeout value, it makes sense to check timeout value in
hci_inquiry() and don't touch hci_req_sync().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: syzbot+be2baed593ea56c6a84c@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/bluetooth/hci_core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 4e4972800370..bdd330527cfa 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1297,6 +1297,12 @@ int hci_inquiry(void __user *arg)
 		goto done;
 	}
 
+	/* Restrict maximum inquiry length to 60 seconds */
+	if (ir.length > 60) {
+		err = -EINVAL;
+		goto done;
+	}
+
 	hci_dev_lock(hdev);
 	if (inquiry_cache_age(hdev) > INQUIRY_CACHE_AGE_MAX ||
 	    inquiry_cache_empty(hdev) || ir.flags & IREQ_CACHE_FLUSH) {
-- 
2.30.2