From ed8b2c86ab77aaa3d7fd688c049ad5e1b922a9c6 Mon Sep 17 00:00:00 2001
From: Reid Wahl <nrwahl@protonmail.com>
Date: Thu, 13 Jan 2022 02:56:55 -0800
Subject: [PATCH] Fix: liblrmd: Avoid double-free during notify operation

This commit fixes a regression introduced by 31c7fa8a, causing a
double-free in notify operations. lrmd_dispatch_internal() assigns the
exit_reason string directly from an XML node to a new lrmd_event_data_t
object (without duplicating), and this string gets freed twice.

Free #1: pcmk__create_history_xml() (reached via callback) calls
lrmd__set_result(), which frees event.exit_reason and sets it to NULL.
Free #2: lrmd_ipc_dispatch() frees the XML node, which contains a
pointer to the exit_reason string just freed, after
lrmd_dispatch_internal() returns.

Prior to 31c7fa8a, pcmk__create_history_xml reset event.rc and
event.op_status but **not** event.exit_reason.

In this commit we simply make a copy of event.exit_reason in
lrmd_dispatch_internal() before the callback. This way we don't have to
worry about whatever happens in the callback, and we can continue to
unset the exit_reason alongside the rc and op_status. The added overhead
should be minimal.

This commit also makes a copy of output. That's not strictly necessary
but adds some futureproofing and allows us to call lrmd__reset_result()
at the end of lrmd_dispatch_internal().

Resolves: RHBZ#2039675

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>
---
 lib/lrmd/lrmd_client.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/lrmd/lrmd_client.c b/lib/lrmd/lrmd_client.c
index ee31bb5ae9..5131a648b7 100644
--- a/lib/lrmd/lrmd_client.c
+++ b/lib/lrmd/lrmd_client.c
@@ -305,9 +305,10 @@ lrmd_dispatch_internal(lrmd_t * lrmd, xmlNode * msg)
         event.user_data = crm_element_value(msg, F_LRMD_RSC_USERDATA_STR);
         event.type = lrmd_event_exec_complete;
 
-        // No need to duplicate the memory, so don't use setter functions
-        event.output = crm_element_value(msg, F_LRMD_RSC_OUTPUT);
-        event.exit_reason = crm_element_value(msg, F_LRMD_RSC_EXIT_REASON);
+        /* output and exit_reason may be freed by a callback */
+        event.output = crm_element_value_copy(msg, F_LRMD_RSC_OUTPUT);
+        lrmd__set_result(&event, event.rc, event.op_status,
+                         crm_element_value(msg, F_LRMD_RSC_EXIT_REASON));
 
         event.params = xml2list(msg);
     } else if (pcmk__str_eq(type, LRMD_OP_NEW_CLIENT, pcmk__str_none)) {
@@ -324,6 +325,7 @@ lrmd_dispatch_internal(lrmd_t * lrmd, xmlNode * msg)
     if (event.params) {
         g_hash_table_destroy(event.params);
     }
+    lrmd__reset_result(&event);
 }
 
 // \return Always 0, to indicate that IPC mainloop source should be kept
-- 
2.27.0