From: Lubomir Rintel <lkundrak@v3.sk>
Date: Thu, 25 Jun 2009 20:57:46 +0000 (+0200)
Subject: Don't enqueue pending signals during global destruction
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=31c91b4357905486e81f901ad079da5735bdb7ba;p=p5sagit%2Fp5-mst-13.2.git

Don't enqueue pending signals during global destruction

Global destruction is not signal-safe. PL_psig_pend may already
be gone when the signal handler is called (with destruct_level > 0).
NULL it before freeing it to prevent a race condition.
---

diff --git a/mg.c b/mg.c
index e9e4214..05a5092 100644
--- a/mg.c
+++ b/mg.c
@@ -1316,13 +1316,14 @@ Perl_csighandler(int sig)
 #endif
 	   (PL_signals & PERL_SIGNALS_UNSAFE_FLAG))
 	/* Call the perl level handler now--
-	 * with risk we may be in malloc() etc. */
+	 * with risk we may be in malloc() or being destructed etc. */
 #if defined(HAS_SIGACTION) && defined(SA_SIGINFO)
 	(*PL_sighandlerp)(sig, NULL, NULL);
 #else
 	(*PL_sighandlerp)(sig);
 #endif
     else {
+	if (!PL_psig_pend) return;
 	/* Set a flag to say this signal is pending, that is awaiting delivery after
 	 * the current Perl opcode completes */
 	PL_psig_pend[sig]++;
diff --git a/perl.c b/perl.c
index e70bf7e..d9ebaca 100644
--- a/perl.c
+++ b/perl.c
@@ -1233,6 +1233,13 @@ perl_destruct(pTHXx)
     PL_psig_ptr = (SV**)NULL;
     Safefree(PL_psig_pend);
     PL_psig_pend = (int*)NULL;
+    {
+	/* We need to NULL PL_psig_pend first, so that
+	   signal handlers know not to use it */
+	int *psig_save = PL_psig_pend;
+	PL_psig_pend = (int*)NULL;
+	Safefree(psig_save);
+    }
     PL_formfeed = NULL;
     nuke_stacks();
     PL_tainting = FALSE;