[PATCH 5.4 107/389] media: hdpvr: fix error value returns in hdpvr_read

Greg Kroah-Hartman
2022-08-23T11:21:32Z

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 7849f1fbbcc4..4f1505b94338 100644
--- a/drivers/media/usb/hdpvr/hdpvr-video.c
+++ b/drivers/media/usb/hdpvr/hdpvr-video.c
@@ -409,7 +409,7 @@ 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