Re: [syzbot] [net?] general protection fault in htb_tcf_block

[Victor Nogueira]

On 31/12/2023 08:04, syzbot wrote:
> HEAD commit:    c2b2ee36250d bridge: cfm: fix enum typo in br_cc_ccm_tx_pa..
> git tree:       net-next
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1041287ee80000

#syz testFrom e63340707ce85f8608e3c3ae3cec1340ef17eede Mon Sep 17 00:00:00 2001
From: Victor Nogueira <victor@xxxxxxxxxxxx>
Date: Thu, 28 Dec 2023 13:18:49 +0000
Subject: [PATCH net-next 1/1] net/sched: We should only add appropriate qdiscs
 blocks to ports' xarray

We should only add qdiscs to the blocks ports' xarray in ingress that
support ingress_block_set/get or in egress that support
egress_block_set/get.

Fixes: 913b47d3424e ("net/sched: Introduce tc block netdev tracking infra")

Signed-off-by: Victor Nogueira <victor@xxxxxxxxxxxx>
Reviewed-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
---
 net/sched/sch_api.c | 34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 299086bb6205..426be81276f1 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1187,23 +1187,29 @@ static int qdisc_block_add_dev(struct Qdisc *sch, struct net_device *dev,
 	struct tcf_block *block;
 	int err;
 
-	block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
-	if (block) {
-		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
-		if (err) {
-			NL_SET_ERR_MSG(extack,
-				       "ingress block dev insert failed");
-			return err;
+	if (sch->ops->ingress_block_get) {
+		block = cl_ops->tcf_block(sch, TC_H_MIN_INGRESS, NULL);
+		if (block) {
+			err = xa_insert(&block->ports, dev->ifindex, dev,
+					GFP_KERNEL);
+			if (err) {
+				NL_SET_ERR_MSG(extack,
+					       "ingress block dev insert failed");
+				return err;
+			}
 		}
 	}
 
-	block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
-	if (block) {
-		err = xa_insert(&block->ports, dev->ifindex, dev, GFP_KERNEL);
-		if (err) {
-			NL_SET_ERR_MSG(extack,
-				       "Egress block dev insert failed");
-			goto err_out;
+	if (sch->ops->egress_block_get) {
+		block = cl_ops->tcf_block(sch, TC_H_MIN_EGRESS, NULL);
+		if (block) {
+			err = xa_insert(&block->ports, dev->ifindex, dev,
+					GFP_KERNEL);
+			if (err) {
+				NL_SET_ERR_MSG(extack,
+					       "Egress block dev insert failed");
+				goto err_out;
+			}
 		}
 	}
 
-- 
2.25.1