From: Philip Prindeville <philipp@redfish-solutions.com>
Date: Wed, 28 Mar 2018 14:25:28 +0000 (-0600)
Subject: Avoid possible SEGVs in select() (in unit tests)
X-Git-Tag: release-2.1.9-beta^2~130
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8818c86caf1deb15d5075de1f7b951d4c60be602;p=libevent

Avoid possible SEGVs in select() (in unit tests)

Per the POSIX definition of select():

http://pubs.opengroup.org/onlinepubs/009696699/functions/pselect.html

"Upon successful completion, the select() function may modify the object
pointed to by the timout argument."

If "struct timeval" pointer is a "static const", it could potentially
be allocated in a RO text segment.  The kernel would then try to copy
back the modified value (with the time remaining) into a read-only
address and SEGV.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
Closes: #614
(cherry picked from commit 33baa4e59fbf9432d77a19c6b2b45402580b79a5)
---

diff --git a/evutil_time.c b/evutil_time.c
index 00fd5fb4..d658b30e 100644
--- a/evutil_time.c
+++ b/evutil_time.c
@@ -141,7 +141,10 @@ evutil_usleep_(const struct timeval *tv)
 	sleep(tv->tv_sec);
 	usleep(tv->tv_usec);
 #else
-	select(0, NULL, NULL, NULL, tv);
+	{
+		struct timeval tv2 = *tv;
+		select(0, NULL, NULL, NULL, &tv2);
+	}
 #endif
 }