binder: Address corner cases in deferred copy and fixup

stable inclusion
from stable-v5.10.157
commit 017de842533f4334d646f1d480f591f4ca9f5c7a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6DKVG
CVE: CVE-2023-20938

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=017de842533f4334d646f1d480f591f4ca9f5c7a



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

commit 2d1746e3 upstream.

When handling BINDER_TYPE_FDA object we are pushing a parent fixup
with a certain skip_size but no scatter-gather copy object, since
the copy is handled standalone.
If BINDER_TYPE_FDA is the last children the scatter-gather copy
loop will never stop to skip it, thus we are left with an item in
the parent fixup list. This will trigger the BUG_ON().

This is reproducible in android when playing a video.
We receive a transaction that looks like this:
    obj[0] BINDER_TYPE_PTR, parent
    obj[1] BINDER_TYPE_PTR, child
    obj[2] BINDER_TYPE_PTR, child
    obj[3] BINDER_TYPE_FDA, child

Fixes: 09184ae9 ("binder: defer copies of pre-patched txn data")
Acked-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Alessandro Astone <ales.astone@gmail.com>
Link: https://lore.kernel.org/r/20220415120015.52684-2-ales.astone@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Zheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>