linux-kernel - [PATCH] bpf: Check the return value of dev_get_by_index

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Date:   Thu, 19 Nov 2020 15:04:28 +0800
From:   xiakaixu1987@...il.com
To:     ast@...nel.org, daniel@...earbox.net, kafai@...com,
        songliubraving@...com, yhs@...com, andrii@...nel.org,
        john.fastabend@...il.com, kpsingh@...omium.org
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org, Kaixu Xia <kaixuxia@...cent.com>
Subject: [PATCH] bpf: Check the return value of dev_get_by_index_rcu()

From: Kaixu Xia <kaixuxia@...cent.com>

The return value of dev_get_by_index_rcu() can be NULL, so here it
is need to check the return value and return error code if it is NULL.

Signed-off-by: Kaixu Xia <kaixuxia@...cent.com>
---
 net/core/filter.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 2ca5eecebacf..1263fe07170a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5573,6 +5573,8 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
 		struct net_device *dev;
 
 		dev = dev_get_by_index_rcu(net, params->ifindex);
+		if (unlikely(!dev))
+			return -EINVAL;
 		if (!is_skb_forwardable(dev, skb))
 			rc = BPF_FIB_LKUP_RET_FRAG_NEEDED;
 	}
-- 
2.20.0