[PATCH 6.6 182/254] net/sched: act_ife: avoid possible NULL deref

Greg Kroah-Hartman
2026-01-28T15:36:25Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 27880b0b0d35ad1c98863d09788254e36f874968 ]

tcf_ife_encode() must make sure ife_encode() does not return NULL.

syzbot reported:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:ife_tlv_meta_encode+0x41/0xa0 net/ife/ife.c:166
CPU: 3 UID: 0 PID: 8990 Comm: syz.0.696 Not tainted syzkaller #0 PREEMPT(full)
Call Trace:
<TASK>
ife_encode_meta_u32+0x153/0x180 net/sched/act_ife.c:101
tcf_ife_encode net/sched/act_ife.c:841 [inline]
tcf_ife_act+0x1022/0x1de0 net/sched/act_ife.c:877
tc_act include/net/tc_wrapper.h:130 [inline]
tcf_action_exec+0x1c0/0xa20 net/sched/act_api.c:1152
tcf_exts_exec include/net/pkt_cls.h:349 [inline]
mall_classify+0x1a0/0x2a0 net/sched/cls_matchall.c:42
tc_classify include/net/tc_wrapper.h:197 [inline]
__tcf_classify net/sched/cls_api.c:1764 [inline]
tcf_classify+0x7f2/0x1380 net/sched/cls_api.c:1860
multiq_classify net/sched/sch_multiq.c:39 [inline]
multiq_enqueue+0xe0/0x510 net/sched/sch_multiq.c:66
dev_qdisc_enqueue+0x45/0x250 net/core/dev.c:4147
__dev_xmit_skb net/core/dev.c:4262 [inline]
__dev_queue_xmit+0x2998/0x46c0 net/core/dev.c:4798

Fixes: 295a6e06d21e ("net/sched: act_ife: Change to use ife module")
Reported-by: syzbot+5cf914f193dffde3bd3c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6970d61d.050a0220.706b.0010.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yotam Gigi <yotam.gi@gmail.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260121133724.3400020-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/act_ife.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 431921204f660..567a58d30df8d 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -821,6 +821,7 @@ static int tcf_ife_encode(struct sk_buff *skb, const struct tc_action *a,
/* could be stupid policy setup or mtu config
* so lets be conservative.. */
if ((action == TC_ACT_SHOT) || exceed_mtu) {
+drop:
qstats_drop_inc(this_cpu_ptr(ife->common.cpu_qstats));
return TC_ACT_SHOT;
}
@@ -829,6 +830,8 @@ static int tcf_ife_encode(struct sk_buff *skb, const struct tc_action *a,
skb_push(skb, skb->dev->hard_header_len);

ife_meta = ife_encode(skb, metalen);
+ if (!ife_meta)
+ goto drop;

spin_lock(&ife->tcf_lock);

@@ -844,8 +847,7 @@ static int tcf_ife_encode(struct sk_buff *skb, const struct tc_action *a,
if (err < 0) {
/* too corrupt to keep around if overwritten */
spin_unlock(&ife->tcf_lock);
- qstats_drop_inc(this_cpu_ptr(ife->common.cpu_qstats));
- return TC_ACT_SHOT;
+ goto drop;
}
skboff += err;
}
--
2.51.0