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[108.214.96.168]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7a370df155csm79129167b3.36.2026.04.07.20.46.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2026 20:46:57 -0700 (PDT) From: Sun Jian To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, shuah@kernel.org Cc: martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, horms@kernel.org, syzbot+619b9ef527f510a57cfc@syzkaller.appspotmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Sun Jian Subject: [PATCH bpf v4 1/2] bpf: reject short IPv4/IPv6 inputs in bpf_prog_test_run_skb Date: Wed, 8 Apr 2026 11:46:22 +0800 Message-ID: <20260408034623.180320-2-sun.jian.kdev@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260408034623.180320-1-sun.jian.kdev@gmail.com> References: <20260408034623.180320-1-sun.jian.kdev@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_prog_test_run_skb() calls eth_type_trans() first and then uses skb->protocol to initialize sk family and address fields for the test run. For IPv4 and IPv6 packets, it may access ip_hdr(skb) or ipv6_hdr(skb) even when the provided test input only contains an Ethernet header. Reject the input earlier if the Ethernet frame carries IPv4/IPv6 EtherType but the L3 header is too short. Fold the IPv4/IPv6 header length checks into the existing protocol switch and return -EINVAL before accessing the network headers. Fixes: fa5cb548ced6 ("bpf: Setup socket family and addresses in bpf_prog_test_run_skb") Reported-by: syzbot+619b9ef527f510a57cfc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=619b9ef527f510a57cfc Signed-off-by: Sun Jian --- net/bpf/test_run.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 178c4738e63b..300e2bfc5a62 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1120,19 +1120,23 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, switch (skb->protocol) { case htons(ETH_P_IP): - sk->sk_family = AF_INET; - if (sizeof(struct iphdr) <= skb_headlen(skb)) { - sk->sk_rcv_saddr = ip_hdr(skb)->saddr; - sk->sk_daddr = ip_hdr(skb)->daddr; + if (skb_headlen(skb) < sizeof(struct iphdr)) { + ret = -EINVAL; + goto out; } + sk->sk_family = AF_INET; + sk->sk_rcv_saddr = ip_hdr(skb)->saddr; + sk->sk_daddr = ip_hdr(skb)->daddr; break; #if IS_ENABLED(CONFIG_IPV6) case htons(ETH_P_IPV6): - sk->sk_family = AF_INET6; - if (sizeof(struct ipv6hdr) <= skb_headlen(skb)) { - sk->sk_v6_rcv_saddr = ipv6_hdr(skb)->saddr; - sk->sk_v6_daddr = ipv6_hdr(skb)->daddr; + if (skb_headlen(skb) < sizeof(struct ipv6hdr)) { + ret = -EINVAL; + goto out; } + sk->sk_family = AF_INET6; + sk->sk_v6_rcv_saddr = ipv6_hdr(skb)->saddr; + sk->sk_v6_daddr = ipv6_hdr(skb)->daddr; break; #endif default: -- 2.43.0