samples/bpf: Fix wrong allocation size in xdp_router_ipv4_user

prefix_key->data allocates three bytes using alloca(), but four bytes are
actually accessed in the program.

Signed-off-by: Rong Tao <rongtao@cestc.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/tencent_F9E2E81922B0C181D05B96DAE5AB0ACE6B06@qq.com

diff --git a/samples/bpf/xdp_router_ipv4_user.c b/samples/bpf/xdp_router_ipv4_user.c
index 683913b..9d41db0 100644 (file)
--- a/samples/bpf/xdp_router_ipv4_user.c
+++ b/samples/bpf/xdp_router_ipv4_user.c
@@ -162,7 +162,7 @@ static void read_route(struct nlmsghdr *nh, int nll)
                                __be32 gw;
                        } *prefix_value;
 
-                       prefix_key = alloca(sizeof(*prefix_key) + 3);
+                       prefix_key = alloca(sizeof(*prefix_key) + 4);
                        prefix_value = alloca(sizeof(*prefix_value));
 
                        prefix_key->prefixlen = 32;