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ubusd_monitor: fix possible null pointer dereference

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This dereference could possibly happen if the calloc call fails as the
return value is unchecked. While at it refactor the code little bit to
make it easier to follow, use safe list iterator and provide return
value for ubusd_monitor_connect.

Signed-off-by: Petr Štetiar <ynezz@true.cz>
This commit is contained in:
Petr Štetiar 2019-12-19 11:10:46 +01:00
parent 060dfbb26d
commit dac6c7c575
1 changed files with 30 additions and 10 deletions
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40
ubusd_monitor.c
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@ -29,7 +29,7 @@ ubusd_monitor_free(struct ubus_monitor *m)
free(m); free(m);
} }
static void static bool
ubusd_monitor_connect(struct ubus_client *cl, struct ubus_msg_buf *ub) ubusd_monitor_connect(struct ubus_client *cl, struct ubus_msg_buf *ub)
{ {
struct ubus_monitor *m; struct ubus_monitor *m;
@ -37,8 +37,28 @@ ubusd_monitor_connect(struct ubus_client *cl, struct ubus_msg_buf *ub)
ubusd_monitor_disconnect(cl); ubusd_monitor_disconnect(cl);
m = calloc(1, sizeof(*m)); m = calloc(1, sizeof(*m));
if (!m)
return false;
m->cl = cl; m->cl = cl;
list_add(&m->list, &monitors); list_add(&m->list, &monitors);
return true;
}
static struct ubus_monitor*
ubusd_monitor_find(struct ubus_client *cl)
{
struct ubus_monitor *m, *tmp;
list_for_each_entry_safe(m, tmp, &monitors, list) {
if (m->cl != cl)
continue;
return m;
}
return NULL;
} }
void void
@ -46,13 +66,11 @@ ubusd_monitor_disconnect(struct ubus_client *cl)
{ {
struct ubus_monitor *m; struct ubus_monitor *m;
list_for_each_entry(m, &monitors, list) { m = ubusd_monitor_find(cl);
if (m->cl != cl) if (!m)
continue;
ubusd_monitor_free(m);
return; return;
}
ubusd_monitor_free(m);
} }
void void
@ -92,13 +110,15 @@ ubusd_monitor_recv(struct ubus_client *cl, struct ubus_msg_buf *ub,
return UBUS_STATUS_PERMISSION_DENIED; return UBUS_STATUS_PERMISSION_DENIED;
if (!strcmp(method, "add")) { if (!strcmp(method, "add")) {
ubusd_monitor_connect(cl, ub); if (!ubusd_monitor_connect(cl, ub))
return 0; return UBUS_STATUS_UNKNOWN_ERROR;
return UBUS_STATUS_OK;
} }
if (!strcmp(method, "remove")) { if (!strcmp(method, "remove")) {
ubusd_monitor_disconnect(cl); ubusd_monitor_disconnect(cl);
return 0; return UBUS_STATUS_OK;
} }
return UBUS_STATUS_METHOD_NOT_FOUND; return UBUS_STATUS_METHOD_NOT_FOUND;