This is a note to let you know that I've just added the patch titled bpf: Move skb->len == 0 checks into __bpf_redirect to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bpf-move-skb-len-0-checks-into-__bpf_redirect.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 27f3aa793d3e2ebdc3b30ed1ef09d963ef9206b4 Author: Stanislav Fomichev <sdf@xxxxxxxxxx> Date: Mon Nov 21 10:03:39 2022 -0800 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@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@xxxxxxxxxx Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 7583ee98c35b..11d254ce3581 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -470,9 +470,6 @@ 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 fb5b9dbf3bc0..68b1509e6188 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2123,6 +2123,11 @@ 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); @@ -2144,7 +2149,7 @@ 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; }