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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, Niels Dossche <dossche.niels@gmail.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 077/287] media: hdpvr: fix error value returns in hdpvr_read
Date:   Tue, 23 Aug 2022 10:24:06 +0200
Message-Id: <20220823080102.838414734@linuxfoundation.org>
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From: Niels Dossche <dossche.niels@gmail.com>

[ Upstream commit 359c27c6ddbde404f44a9c0d3ec88ccd1e2042f2 ]

Error return values are supposed to be negative in hdpvr_read. Most
error returns are currently handled via an unsigned integer "ret". When
setting a negative error value to "ret", the value actually becomes a
large positive value, because "ret" is unsigned. Later on, the "ret"
value is returned. But as ssize_t is a 64-bit signed number, the error
return value stays a large positive integer instead of a negative
integer. This can cause an error value to be interpreted as the read
size, which can cause a buffer overread for applications relying on the
returned size.

Fixes: 9aba42efe85b ("V4L/DVB (11096): V4L2 Driver for the Hauppauge HD PVR usb capture device")
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/media/usb/hdpvr/hdpvr-video.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/usb/hdpvr/hdpvr-video.c b/drivers/media/usb/hdpvr/hdpvr-video.c
index ce46f8721470..1fb2cdd9c4b2 100644
--- a/drivers/media/usb/hdpvr/hdpvr-video.c
+++ b/drivers/media/usb/hdpvr/hdpvr-video.c
@@ -413,7 +413,7 @@ static ssize_t hdpvr_read(struct file *file, char __user *buffer, size_t count,
 	struct hdpvr_device *dev = video_drvdata(file);
 	struct hdpvr_buffer *buf = NULL;
 	struct urb *urb;
-	unsigned int ret = 0;
+	int ret = 0;
 	int rem, cnt;
 
 	if (*pos)
-- 
2.35.1