statefiles: fix off-by-one-bug

The string with the final hostsfile name is "%s.%s", so we need two
extra bytes for the separating "." and for the trailing null byte.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/322
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/statefiles.c b/src/statefiles.c
index ed45f5559dc061b33bfd35073d0ab79833d51a81..a5d4e3ea6aeb8bd3e55594706901b37a814e13f0 100644 (file)
--- a/src/statefiles.c
+++ b/src/statefiles.c
@@ -103,7 +103,7 @@ static void statefiles_write_hosts(time_t now)
        avl_for_each_element(&interfaces, ctxt.iface, avl) {
                char *hostsfile;
 
-               hostsfile = alloca(strlen(ODHCPD_HOSTS_FILE_PREFIX) + strlen(ctxt.iface->name) + 1);
+               hostsfile = alloca(strlen(ODHCPD_HOSTS_FILE_PREFIX) + 1 + strlen(ctxt.iface->name) + 1);
                sprintf(hostsfile, "%s.%s", ODHCPD_HOSTS_FILE_PREFIX, ctxt.iface->name);
 
                fd = openat(config.dhcp_hostsdir_fd, tmp_hostsfile, O_CREAT | O_WRONLY | O_CLOEXEC, 0644);