From: David Härdeman <david@hardeman.nu>
Date: Sun, 23 Nov 2025 18:34:51 +0000 (+0100)
Subject: statefiles: fix off-by-one-bug
X-Git-Url: http://git.openwrt.org/?a=commitdiff_plain;h=9b9ea96ca90e736d0668bfa6c3011c36efabbc8d;p=project%2Fodhcpd.git

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 <david@hardeman.nu>
Link: https://github.com/openwrt/odhcpd/pull/322
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---

diff --git a/src/statefiles.c b/src/statefiles.c
index ed45f55..a5d4e3e 100644
--- 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);