media: dvb-usb-v2: gl861: Fix null-ptr-deref in gl861_i2c_master_xfer

stable inclusion
from stable-v5.10.197
commit 578b67614ae0e4fba3945b66a4c8f9ae77115bcb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I96Q8P

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=578b67614ae0e4fba3945b66a4c8f9ae77115bcb



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[ Upstream commit b97719a6 ]

In gl861_i2c_master_xfer, msg is controlled by user. When msg[i].buf
is null and msg[i].len is zero, former checks on msg[i].buf would be
passed. Malicious data finally reach gl861_i2c_master_xfer. If accessing
msg[i].buf[0] without sanity check, null ptr deref would happen.
We add check on msg[i].len to prevent crash.

Similar commit:
commit 0ed554fd
("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()")

Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>