media: hdpvr: fix error value returns in hdpvr_read

stable inclusion
from stable-v5.10.137
commit bb480bffc1fd439f12635302957ed932bb1a5e9f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bb480bffc1fd439f12635302957ed932bb1a5e9f



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[ Upstream commit 359c27c6 ]

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: 9aba42ef ("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>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>