mdadm: monitor: fix nullptr dereference when get_md_name() returns NULL

Function add_new_arrays() expects that function get_md_name() should
return pointer to devname, but also get_md_name() may return NULL. So
check the pointer before use it in add_new_arrays().

Signed-off-by: Sergey Vidishev <sergeyv@yandex-team.ru>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/Monitor.c b/Monitor.c
index 1cd378b7a95697d65bf0a72775ee66ebc8c55316..a5300329b464b8108e2deec305cf1418a82ca5db 100644 (file)
--- a/Monitor.c
+++ b/Monitor.c
@@ -687,6 +687,7 @@ static int add_new_arrays(struct mdstat_ent *mdstat, struct state **statelist,
 {
        struct mdstat_ent *mse;
        int new_found = 0;
+       char *name;
 
        for (mse=mdstat; mse; mse=mse->next)
                if (mse->devnm[0] &&
@@ -697,7 +698,14 @@ static int add_new_arrays(struct mdstat_ent *mdstat, struct state **statelist,
                        struct state *st = xcalloc(1, sizeof *st);
                        mdu_array_info_t array;
                        int fd;
-                       st->devname = xstrdup(get_md_name(mse->devnm));
+
+                       name = get_md_name(mse->devnm);
+                       if (!name) {
+                               free(st);
+                               continue;
+                       }
+
+                       st->devname = xstrdup(name);
                        if ((fd = open(st->devname, O_RDONLY)) < 0 ||
                            ioctl(fd, GET_ARRAY_INFO, &array)< 0) {
                                /* no such array */