shared: correctly propagate possible allocation errors

instead of just asserting in case the memstream couldn't be resized.

Found by Nallocufuzz.

diff --git a/src/shared/json.c b/src/shared/json.c
index 8962173b3aefae94bc5d24e51b7a589df2c0e2fd..904b26f9867248039edf8ae8ab7857bc8ce484ea 100644 (file)
--- a/src/shared/json.c
+++ b/src/shared/json.c
@@ -1788,7 +1788,9 @@ int json_variant_format(JsonVariant *v, JsonFormatFlags flags, char **ret) {
                 if (!f)
                         return -ENOMEM;
 
-                json_variant_dump(v, flags, f, NULL);
+                r = json_variant_dump(v, flags, f, NULL);
+                if (r < 0)
+                        return r;
 
                 /* Add terminating 0, so that the output buffer is a valid string. */
                 fputc('\0', f);