From: Victor Stinner <vstinner@python.org>
Date: Thu, 8 Sep 2022 10:20:22 +0000 (+0200)
Subject: gh-96652: Fix faulthandler chained signal without sigaction() (#96666)
X-Git-Tag: v3.12.0a1~449
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c580a81af91af4b9df85e466f8b48c3c9c86c3df;p=thirdparty%2FPython%2Fcpython.git

gh-96652: Fix faulthandler chained signal without sigaction() (#96666)

Fix the faulthandler implementation of faulthandler.register(signal,
chain=True) if the sigaction() function is not available: don't call
the previous signal handler if it's NULL.
---

diff --git a/Misc/NEWS.d/next/Library/2022-09-07-22-49-37.gh-issue-96652.YqOKxI.rst b/Misc/NEWS.d/next/Library/2022-09-07-22-49-37.gh-issue-96652.YqOKxI.rst
new file mode 100644
index 000000000000..1d04db7b2a25
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-09-07-22-49-37.gh-issue-96652.YqOKxI.rst
@@ -0,0 +1,3 @@
+Fix the faulthandler implementation of ``faulthandler.register(signal,
+chain=True)`` if the ``sigaction()`` function is not available: don't call
+the previous signal handler if it's NULL. Patch by Victor Stinner.
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
index b36268782bda..8b5cf276afc1 100644
--- a/Modules/faulthandler.c
+++ b/Modules/faulthandler.c
@@ -862,7 +862,7 @@ faulthandler_user(int signum)
         errno = save_errno;
     }
 #else
-    if (user->chain) {
+    if (user->chain && user->previous != NULL) {
         errno = save_errno;
         /* call the previous signal handler */
         user->previous(signum);