From: Stanislav Fomichev <sdf@google.com>
Date: Mon, 21 Nov 2022 18:03:39 +0000 (-0800)
Subject: bpf: Move skb->len == 0 checks into __bpf_redirect
X-Git-Tag: v6.1.8~1595
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=21f15d8ffdb46e95d721810c2d7ed2149fff397c;p=platform%2Fkernel%2Flinux-starfive.git

bpf: Move skb->len == 0 checks into __bpf_redirect

[ Upstream commit 114039b342014680911c35bd6b72624180fd669a ]

To avoid potentially breaking existing users.

Both mac/no-mac cases have to be amended; mac_header >= network_header
is not enough (verified with a new test, see next patch).

Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index fcb3e6c..6094ef7 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -980,9 +980,6 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb)
 {
 	struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb;
 
-	if (!skb->len)
-		return -EINVAL;
-
 	if (!__skb)
 		return 0;
 
diff --git a/net/core/filter.c b/net/core/filter.c
index bb0136e..b35f642 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2124,6 +2124,11 @@ static int __bpf_redirect_no_mac(struct sk_buff *skb, struct net_device *dev,
 {
 	unsigned int mlen = skb_network_offset(skb);
 
+	if (unlikely(skb->len <= mlen)) {
+		kfree_skb(skb);
+		return -ERANGE;
+	}
+
 	if (mlen) {
 		__skb_pull(skb, mlen);
 
@@ -2145,7 +2150,7 @@ static int __bpf_redirect_common(struct sk_buff *skb, struct net_device *dev,
 				 u32 flags)
 {
 	/* Verify that a link layer header is carried */
-	if (unlikely(skb->mac_header >= skb->network_header)) {
+	if (unlikely(skb->mac_header >= skb->network_header || skb->len == 0)) {
 		kfree_skb(skb);
 		return -ERANGE;
 	}