linux-kernel - [PATCH] net: sched: sch: null pointer dereference in htb_offload_move

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Message-Id: <20230216104939.3553390-1-alok.a.tiwari@oracle.com>
Date:   Thu, 16 Feb 2023 02:49:40 -0800
From:   Alok Tiwari <alok.a.tiwari@...cle.com>
To:     netdev@...r.kernel.org
Cc:     alok.a.tiwari@...cle.com, darren.kenny@...cle.com,
        linux-kernel@...r.kernel.org, jhs@...atatu.com,
        xiyou.wangcong@...il.com, jiri@...nulli.us, kuba@...nel.org,
        simon.horman@...igine.com, keescook@...omium.org
Subject: [PATCH] net: sched: sch: null pointer dereference in htb_offload_move_qdisc()

A possible case of null pointer dereference detected by static analyzer
htb_destroy_class_offload() is calling htb_find() which can return NULL value
for invalid class id, moved_cl=htb_find(classid, sch);
in that case it should not pass 'moved_cl' to htb_offload_move_qdisc()
if 'moved_cl' is NULL pointer return -EINVAL.

Signed-off-by: Alok Tiwari <alok.a.tiwari@...cle.com>
---
 net/sched/sch_htb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 92f2975b6a82..5a96d9ea3221 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1601,6 +1601,8 @@ static int htb_destroy_class_offload(struct Qdisc *sch, struct htb_class *cl,
 		u32 classid = TC_H_MAJ(sch->handle) |
 			      TC_H_MIN(offload_opt.classid);
 		struct htb_class *moved_cl = htb_find(classid, sch);
+		if (WARN_ON_ONCE(!moved_cl))
+			return -EINVAL;
 
 		htb_offload_move_qdisc(sch, moved_cl, cl, destroying);
 	}
-- 
2.39.1