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, Jozef Balga <jozef.balga@gmail.com>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 01/41] media: af9035: prevent buffer overflow on write
Date:   Thu, 18 Oct 2018 19:54:16 +0200
Message-Id: <20181018175416.858412783@linuxfoundation.org>
In-Reply-To: <20181018175416.718399607@linuxfoundation.org>
References: <20181018175416.718399607@linuxfoundation.org>
User-Agent: quilt/0.65
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

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

From: Jozef Balga <jozef.balga@gmail.com>

[ Upstream commit 312f73b648626a0526a3aceebb0a3192aaba05ce ]

When less than 3 bytes are written to the device, memcpy is called with
negative array size which leads to buffer overflow and kernel panic. This
patch adds a condition and returns -EOPNOTSUPP instead.
Fixes bugzilla issue 64871

[mchehab+samsung@kernel.org: fix a merge conflict and changed the
 condition to match the patch's comment, e. g. len == 3 could
 also be valid]
Signed-off-by: Jozef Balga <jozef.balga@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/usb/dvb-usb-v2/af9035.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/media/usb/dvb-usb-v2/af9035.c
+++ b/drivers/media/usb/dvb-usb-v2/af9035.c
@@ -402,8 +402,10 @@ static int af9035_i2c_master_xfer(struct
 			if (msg[0].addr == state->af9033_i2c_addr[1])
 				reg |= 0x100000;
 
-			ret = af9035_wr_regs(d, reg, &msg[0].buf[3],
-					msg[0].len - 3);
+			ret = (msg[0].len >= 3) ? af9035_wr_regs(d, reg,
+							         &msg[0].buf[3],
+							         msg[0].len - 3)
+					        : -EOPNOTSUPP;
 		} else {
 			/* I2C write */
 			u8 buf[MAX_XFER_SIZE];