json: always allocate at least sizeof(JsonVariant) bytes

ubsan apparently doesn't like us being too smart here. Given the
difference is just a few bytes, let's avoid the noise.

Fixes: #13020

diff --git a/src/shared/json.c b/src/shared/json.c
index a068049b57f1863902ed9dec1665b6102ed3275d..f1bb50cfa2c8ce84df08ac44799b77a9fabe2596 100644 (file)
--- a/src/shared/json.c
+++ b/src/shared/json.c
@@ -279,7 +279,8 @@ static int json_variant_new(JsonVariant **ret, JsonVariantType type, size_t spac
 
         assert_return(ret, -EINVAL);
 
-        v = malloc0(offsetof(JsonVariant, value) + space);
+        v = malloc0(MAX(sizeof(JsonVariant),
+                        offsetof(JsonVariant, value) + space));
         if (!v)
                 return -ENOMEM;
 
@@ -1664,7 +1665,8 @@ static int json_variant_copy(JsonVariant **nv, JsonVariant *v) {
         default:
                 /* Everything else copy by reference */
 
-                c = malloc0(offsetof(JsonVariant, reference) + sizeof(JsonVariant*));
+                c = malloc0(MAX(sizeof(JsonVariant),
+                                offsetof(JsonVariant, reference) + sizeof(JsonVariant*)));
                 if (!c)
                         return -ENOMEM;
 
@@ -1677,7 +1679,8 @@ static int json_variant_copy(JsonVariant **nv, JsonVariant *v) {
                 return 0;
         }
 
-        c = malloc0(offsetof(JsonVariant, value) + k);
+        c = malloc0(MAX(sizeof(JsonVariant),
+                        offsetof(JsonVariant, value) + k));
         if (!c)
                 return -ENOMEM;