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

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

Origin: https://git.kernel.org/linus/a2965c7be0522eaa18808684b7b82b248515511b
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2023-23455

If asked to drop a packet via TC_ACT_SHOT it is unsafe to assume
res.class contains a valid pointer
Fixes: b0188d4dbe5f ("[NET_SCHED]: sch_atm: Lindent")
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name net-sched-atm-dont-intepret-cls-results-when-asked-t.patch