lib: fix segfault on freebsd when using vsnprintf() incorrectly

FreeBSD's libc segfaults when vsnprintf() is called with a null
format string. Add a null check before calling vsnprintf() to
resolve this problem.

Fixes #3537

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

diff --git a/lib/northbound_cli.c b/lib/northbound_cli.c
index acde0ead025ac47d62750a6baff0480a06995cd0..2b024ace9304f0b9753dc30f2e50ac2aa4469956 100644 (file)
--- a/lib/northbound_cli.c
+++ b/lib/northbound_cli.c
@@ -79,8 +79,7 @@ void nb_cli_enqueue_change(struct vty *vty, const char *xpath,
 int nb_cli_apply_changes(struct vty *vty, const char *xpath_base_fmt, ...)
 {
        struct nb_config *candidate_transitory;
-       char xpath_base[XPATH_MAXLEN];
-       va_list ap;
+       char xpath_base[XPATH_MAXLEN] = {};
        bool error = false;
        int ret;
 
@@ -94,9 +93,13 @@ int nb_cli_apply_changes(struct vty *vty, const char *xpath_base_fmt, ...)
        candidate_transitory = nb_config_dup(vty->candidate_config);
 
        /* Parse the base XPath format string. */
-       va_start(ap, xpath_base_fmt);
-       vsnprintf(xpath_base, sizeof(xpath_base), xpath_base_fmt, ap);
-       va_end(ap);
+       if (xpath_base_fmt) {
+               va_list ap;
+
+               va_start(ap, xpath_base_fmt);
+               vsnprintf(xpath_base, sizeof(xpath_base), xpath_base_fmt, ap);
+               va_end(ap);
+       }
 
        /* Edit candidate configuration. */
        for (size_t i = 0; i < vty->num_cfg_changes; i++) {

diff --git a/lib/northbound_cli.h b/lib/northbound_cli.h
index 362a4bc32528c262d01aaaa8c0a60b74c9cc11b4..884f2509412dcc3804d1af1ec0257a5474f7ea42 100644 (file)
--- a/lib/northbound_cli.h
+++ b/lib/northbound_cli.h
@@ -60,7 +60,7 @@ extern void nb_cli_enqueue_change(struct vty *vty, const char *xpath,
  *
  * xpath_base_fmt
  *    Prepend the given XPath (absolute or relative) to all enqueued
- *    configuration changes.
+ *    configuration changes. This is an optional parameter.
  *
  * Returns:
  *    CMD_SUCCESS on success, CMD_WARNING_CONFIG_FAILED otherwise.