From: Vsevolod Stakhov <vsevolod@rspamd.com>
Date: Tue, 23 Dec 2025 10:13:43 +0000 (+0000)
Subject: [Fix] Restore Lua stack properly in second-pass MIME detection
X-Git-Tag: 3.14.3~31
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=77ac680ff0a9ec8a9a9bb66464d82d7a48094b46;p=thirdparty%2Frspamd.git

[Fix] Restore Lua stack properly in second-pass MIME detection

Fix lua_settop(L, 0) which cleared the entire Lua stack instead
of restoring to the previous state, causing segfaults when
process_message() was called from Lua unit tests.
---

diff --git a/src/libmime/message.c b/src/libmime/message.c
index ad2aaf21c3..2bc8fbdedb 100644
--- a/src/libmime/message.c
+++ b/src/libmime/message.c
@@ -1637,6 +1637,7 @@ void rspamd_message_process(struct rspamd_task *task)
 		rspamd_mime_parser_get_lua_magic_cbref(task->cfg->mime_parser_cfg) != -1) {
 		unsigned int j;
 		struct rspamd_mime_part *pp;
+		int second_pass_old_top = lua_gettop(L);
 		PTR_ARRAY_FOREACH(MESSAGE_FIELD(task, parts), j, pp)
 		{
 			gboolean needs_refine = FALSE;
@@ -1708,8 +1709,7 @@ void rspamd_message_process(struct rspamd_task *task)
 				else {
 					msg_err_task("second-pass detect type: %s", lua_tostring(L, -1));
 				}
-				/* restore stack */
-				lua_settop(L, 0);
+				lua_settop(L, second_pass_old_top);
 			}
 		}
 	}