File sysstat-fix-possible-race-in-signal-handler.patch of Package sysstat.8010

Overview Repositories Revisions Requests Users Attributes Meta

File sysstat-fix-possible-race-in-signal-handler.patch of Package sysstat.8010

From c3de69658006af0e0e3b7746e8646b8b4cdd2860 Mon Sep 17 00:00:00 2001
From: Sebastien GODARD <sysstat@users.noreply.github.com>
Date: Sun, 2 Nov 2014 18:02:06 +0100
Subject: [PATCH] sadc: Fix possible race condition in signal handler code

Commit 1b52f939 tried to stop sending SIGINT to init process.
But there may be very small time window between parent ID
validation and sending kill signal to parent. If sar dies
during this window (though the chance is very small) we end up
sending signal to init.

This patch fixes above issue.

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>
---
 sadc.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/sadc.c b/sadc.c
index 4d737d0..0ccc81f 100644
--- a/sadc.c
+++ b/sadc.c
@@ -233,21 +233,19 @@ void alarm_handler(int sig)
  */
 void int_handler(int sig)
 {
-	if (!optz) {
-		/* sadc hasn't been called by sar */
+	pid_t ppid = getppid();
+
+	if (!optz || (ppid == 1)) {
+		/* sadc hasn't been called by sar or sar process is already dead */
 		exit(1);
 	}
 	
-	/* Don't send signal to init process!! */
-	if (getppid() == 1)
-		return;
-
 	/*
 	 * When starting sar then pressing ctrl/c, SIGINT is received
 	 * by sadc, not sar. So send SIGINT to sar so that average stats
 	 * can be displayed.
 	 */
-	if (kill(getppid(), SIGINT) < 0) {
+	if (kill(ppid, SIGINT) < 0) {
 		exit(1);
 	}
 }
-- 
1.8.5.6

Places

File sysstat-fix-possible-race-in-signal-handler.patch of Package sysstat.8010

Places