svn commit: r314936 - head/sys/x86/isa

[Eric van Gyzen]

Author: vangyzen
Date: Thu Mar  9 02:19:30 2017
New Revision: 314936
URL: https://svnweb.freebsd.org/changeset/base/314936

Log:
  Validate values read from the RTC before trying BCD decoding
  
  Submitted by:	cem
  Reported by:	Michael Gmelin <freebsd at grem.de>
  Tested by:	Oleksandr Tymoshenko <gonzo at bluezbox.com>
  Sponsored by:	Dell EMC

Modified:
  head/sys/x86/isa/atrtc.c

Modified: head/sys/x86/isa/atrtc.c
==============================================================================
--- head/sys/x86/isa/atrtc.c	Thu Mar  9 01:26:10 2017	(r314935)
+++ head/sys/x86/isa/atrtc.c	Thu Mar  9 02:19:30 2017	(r314936)
@@ -102,7 +102,12 @@ writertc(int reg, u_char val)
 static __inline int
 readrtc(int port)
 {
-	return(bcd2bin(rtcin(port)));
+	int readval;
+
+	readval = rtcin(port);
+	if (readval >= 0 && (readval & 0xf) < 0xa && (readval & 0xf0) < 0xa0)
+		return (bcd2bin(readval));
+	return (0);
 }
 
 static void