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@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files 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);