From: Willy Tarreau <w@1wt.eu>
Date: Tue, 21 Jun 2016 15:29:46 +0000 (+0200)
Subject: BUG/MINOR: external-checks: do not unblock undesired signals
X-Git-Tag: v1.7-dev4~58
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=ebc92440594459457005e13c5356ff26e117d8aa;p=thirdparty%2Fhaproxy.git

BUG/MINOR: external-checks: do not unblock undesired signals

The external checks code makes use of block_sigchld() and unblock_sigchld()
to ensure nobody modifies the signals list while they're being manipulated.
It happens that these functions clear the list of blocked signals, so they
can possibly have a side effect if other signals are blocked. For now no
other signal is blocked but it may very well change in the future so rather
correctly use SIG_BLOCK/SIG_UNBLOCK instead of touching unrelated signals.

This fix should be backported to 1.6 for correctness.
---

diff --git a/src/checks.c b/src/checks.c
index ee0295edf3..b925d05613 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -1541,14 +1541,15 @@ void block_sigchld(void)
 	sigset_t set;
 	sigemptyset(&set);
 	sigaddset(&set, SIGCHLD);
-	assert(sigprocmask(SIG_SETMASK, &set, NULL) == 0);
+	assert(sigprocmask(SIG_BLOCK, &set, NULL) == 0);
 }
 
 void unblock_sigchld(void)
 {
 	sigset_t set;
 	sigemptyset(&set);
-	assert(sigprocmask(SIG_SETMASK, &set, NULL) == 0);
+	sigaddset(&set, SIGCHLD);
+	assert(sigprocmask(SIG_UNBLOCK, &set, NULL) == 0);
 }
 
 /* Call with SIGCHLD blocked */