stable inclusion
from stable-v5.10.121
commit 7a79ab25968408e6ce08770015cc9ba758827fd9
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7a79ab25968408e6ce08770015cc9ba758827fd9

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

[ Upstream commit 261f3338 ]

The list iterator will point to a bogus position containing HEAD if
the list is empty or the element is not found in list. This case
should be checked before any use of the iterator, otherwise it will
lead to a invalid memory access. The missing check here is before
"pin = iterm->id;", just add check here to fix the security bug.

In addition, the list iterator value will *always* be set and non-NULL
by list_for_each_entry(), so it is incorrect to assume that the iterator
value will be NULL if the element is not found in list, considering
the (mis)use here: "if (iterm == NULL".

Use a new value 'it' as the list iterator, while use the old value
'iterm' as a dedicated pointer to point to the found element, which
1. can fix this bug, due to 'iterm' is NULL only if it's not found.
2. do not need to change all the uses of 'iterm' after the loop.
3. can also limit the scope of the list iterator 'it' *only inside*
   the traversal loop by simply declaring 'it' inside the loop in the
   future, as usage of the iterator outside of the list_for_each_entry
   is considered harmful. https://lkml.org/lkml/2022/2/17/1032

Fixes: d5e90b7a ("[media] uvcvideo: Move to video_ioctl2")
Signed-off-by: NXiaomeng Tong <xiam0nd.tong@gmail.com>
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>