From: Eli Zaretskii <eliz@gnu.org>
Date: Thu, 15 Dec 2016 16:18:59 +0000 (+0200)
Subject: Prevent crashes in xg_select due to concurrency
X-Git-Tag: emacs-26.0.90~1076
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=4fbda463dca50f630c31a2602bd34849f4b51e51;p=emacs.git

Prevent crashes in xg_select due to concurrency

* src/xgselect.c (xg_select): Don't call Glib functions that use
'context' if we failed to acquire it.  This means some other
thread owns the context, in which case both using the context and
calling block_input/unblock_input will step on that thread's toes
and eventually lead to crashes.  (Bug#25172)
---

diff --git a/src/xgselect.c b/src/xgselect.c
index 2f23764ae41..a9461a5df5a 100644
--- a/src/xgselect.c
+++ b/src/xgselect.c
@@ -150,7 +150,7 @@ xg_select (int fds_lim, fd_set *rfds, fd_set *wfds, fd_set *efds,
 #else
   need_to_dispatch = true;
 #endif
-  if (need_to_dispatch)
+  if (need_to_dispatch && context_acquired)
     {
       int pselect_errno = errno;
       /* Prevent g_main_dispatch recursion, that would occur without