From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Thu, 31 Oct 2019 20:06:59 -0700
Subject: net: cls_bpf: fix NULL deref on offload filter removal
Patch-mainline: v5.4-rc6
Git-commit: 41aa29a58b5f7f7be43f35372ef411f304a87a0d
References: bsc#1154353

Commit 401192113730 ("net: sched: refactor block offloads counter
usage") missed the fact that either new prog or old prog may be
NULL.

Fixes: 401192113730 ("net: sched: refactor block offloads counter usage")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/cls_bpf.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -162,16 +162,20 @@ static int cls_bpf_offload_cmd(struct tc
 	cls_bpf.name = obj->bpf_name;
 	cls_bpf.exts_integrated = obj->exts_integrated;
 
-	if (oldprog)
+	if (oldprog && prog)
 		err = tc_setup_cb_replace(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
 					  skip_sw, &oldprog->gen_flags,
 					  &oldprog->in_hw_count,
 					  &prog->gen_flags, &prog->in_hw_count,
 					  true);
-	else
+	else if (prog)
 		err = tc_setup_cb_add(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
 				      skip_sw, &prog->gen_flags,
 				      &prog->in_hw_count, true);
+	else
+		err = tc_setup_cb_destroy(block, tp, TC_SETUP_CLSBPF, &cls_bpf,
+					  skip_sw, &oldprog->gen_flags,
+					  &oldprog->in_hw_count, true);
 
 	if (prog && err) {
 		cls_bpf_offload_cmd(tp, oldprog, prog, extack);