modprobe: protect against possible SEGV
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 2860ae0..f339fbd 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -80,12 +80,14 @@
static char *gather_options_str(char *opts, const char *append)
{
/* Speed-optimized. We call gather_options_str many times. */
- if (opts == NULL) {
- opts = xstrdup(append);
- } else {
- int optlen = strlen(opts);
- opts = xrealloc(opts, optlen + strlen(append) + 2);
- sprintf(opts + optlen, " %s", append);
+ if (append) {
+ if (opts == NULL) {
+ opts = xstrdup(append);
+ } else {
+ int optlen = strlen(opts);
+ opts = xrealloc(opts, optlen + strlen(append) + 2);
+ sprintf(opts + optlen, " %s", append);
+ }
}
return opts;
}
