netdev - [PATCH net 2/3] net: cls_bpf: fix NULL deref on offload filter removal

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Message-Id: <20191101030700.13080-3-jakub.kicinski@netronome.com>
Date:   Thu, 31 Oct 2019 20:06:59 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     alexei.starovoitov@...il.com, daniel@...earbox.net,
        bpf@...r.kernel.org, netdev@...r.kernel.org,
        oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net 2/3] net: cls_bpf: fix NULL deref on offload filter removal

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@...ronome.com>
---
CC: Vlad Buslov <vladbu@...lanox.com>

 net/sched/cls_bpf.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index bf10bdaf5012..8229ed4a67be 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -162,16 +162,20 @@ static int cls_bpf_offload_cmd(struct tcf_proto *tp, struct cls_bpf_prog *prog,
 	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);
-- 
2.23.0