Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Andrey Konovalov <andreyknvl@google.com>,
        Firo Yang <firogm@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 095/190] hdlcdrv: Fix divide by zero in hdlcdrv_ioctl
Date:   Wed, 11 Apr 2018 20:35:41 +0200
Message-Id: <20180411183556.135523359@linuxfoundation.org>
In-Reply-To: <20180411183550.114495991@linuxfoundation.org>
References: <20180411183550.114495991@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Firo Yang <firogm@gmail.com>


[ Upstream commit fb3ce90b7d7761b6f7f28f0ff5c456ef6b5229a1 ]

syszkaller fuzzer triggered a divide by zero, when set calibration
through ioctl().

To fix it, test 'bitrate' if it is negative or 0, just return -EINVAL.

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Firo Yang <firogm@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/hamradio/hdlcdrv.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/hamradio/hdlcdrv.c
+++ b/drivers/net/hamradio/hdlcdrv.c
@@ -574,6 +574,8 @@ static int hdlcdrv_ioctl(struct net_devi
 	case HDLCDRVCTL_CALIBRATE:
 		if(!capable(CAP_SYS_RAWIO))
 			return -EPERM;
+		if (s->par.bitrate <= 0)
+			return -EINVAL;
 		if (bi.data.calibrate > INT_MAX / s->par.bitrate)
 			return -EINVAL;
 		s->hdlctx.calibrate = bi.data.calibrate * s->par.bitrate / 16;