net: sched: atm: dont intepret cls results when asked to drop

stable inclusion
from stable-v5.10.162
commit 5f65f48516bfeebaab1ccc52c8fad698ddf21282
category: bugfix
bugzilla: 188250, https://gitee.com/src-openeuler/kernel/issues/I6AQG9
CVE: CVE-2023-23455

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5f65f48516bfeebaab1ccc52c8fad698ddf21282



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

[ Upstream commit a2965c7b ]

If asked to drop a packet via TC_ACT_SHOT it is unsafe to assume
res.class contains a valid pointer
Fixes: b0188d4d ("[NET_SCHED]: sch_atm: Lindent")

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>