From 836b2fe544a5e9b5ce116622cb36fba33838c6fd Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 4 Sep 2026 01:33:23 -0700 Subject: selftests/bpf: Check that JMP32 pointer vs zero jumps are not predicted Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which the verifier used to skip, contains an out of bounds map value access, hence w/o the previous patch the program is accepted. See previous patch for detailed description. Reported-by: Nicholas Carlini Suggested-by: Nicholas Carlini Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- samples/bpf/parse_simple.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 samples/bpf/parse_simple.c (limited to 'samples/bpf/parse_simple.c') diff --git a/samples/bpf/parse_simple.c b/samples/bpf/parse_simple.c new file mode 100644 index 000000000..4a486cb1e --- /dev/null +++ b/samples/bpf/parse_simple.c @@ -0,0 +1,49 @@ +/* Copyright (c) 2016 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#define KBUILD_MODNAME "foo" +#include +#include +#include +#include +#include +#include +#include +#include + +#define DEFAULT_PKTGEN_UDP_PORT 9 + +/* copy of 'struct ethhdr' without __packed */ +struct eth_hdr { + unsigned char h_dest[ETH_ALEN]; + unsigned char h_source[ETH_ALEN]; + unsigned short h_proto; +}; + +SEC("simple") +int handle_ingress(struct __sk_buff *skb) +{ + void *data = (void *)(long)skb->data; + struct eth_hdr *eth = data; + struct iphdr *iph = data + sizeof(*eth); + struct udphdr *udp = data + sizeof(*eth) + sizeof(*iph); + void *data_end = (void *)(long)skb->data_end; + + /* single length check */ + if (data + sizeof(*eth) + sizeof(*iph) + sizeof(*udp) > data_end) + return 0; + + if (eth->h_proto != htons(ETH_P_IP)) + return 0; + if (iph->protocol != IPPROTO_UDP || iph->ihl != 5) + return 0; + if (ip_is_fragment(iph)) + return 0; + if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT)) + return TC_ACT_SHOT; + return 0; +} +char _license[] SEC("license") = "GPL"; -- cgit v1.3.1