UPSTREAM: net_sched: reject TCF_EM_SIMPLE case for complex ematch module

[ Upstream commit 9cd3fd2054c3b3055163accbf2f31a4426f10317 ]

When TCF_EM_SIMPLE was introduced, it is supposed to be convenient
for ematch implementation:

https://lore.kernel.org/all/20050105110048.GO26856@postel.suug.ch/



"You don't have to, providing a 32bit data chunk without TCF_EM_SIMPLE
set will simply result in allocating & copy. It's an optimization,
nothing more."

So if an ematch module provides ops->datalen that means it wants a
complex data structure (saved in its em->data) instead of a simple u32
value. We should simply reject such a combination, otherwise this u32
could be misinterpreted as a pointer.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-and-tested-by:  <syzbot+4caeae4c7103813598ae@syzkaller.appspotmail.com>
Reported-by: Jun Nie <jun.nie@linaro.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Bug: 262113355
Bug: 262114215
Change-Id: I03be57351f76f699d4635cf31178e0f3a19e61a5
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>