From fbf05b8793e85f76f79eed1a0d130217cb53ff55 Mon Sep 17 00:00:00 2001
From: Chris Tallon <chris@vomp.tv>
Date: Thu, 30 Mar 2017 18:20:45 +0100
Subject: [PATCH] Fix segfault when using subtitles

The segfault occurs in pthread_exit which points at memory corruption...

The problem:
Play live/recording, switch subtitles on. No subtitle packets arrive from
the demuxer (a channel without subtitles or just a part of a programme with
no dialogue).
Navigate or stop (anything to switch from playing to stopped).
cTimeMs returns a small positive integer because it has never been
initialised with anything other than 0.
This value is negated inside an unsigned creating a very large number
for "wakeup" which causes targetTime to overflow to
a negative number. This is supplied to pthread_cond_timedwait which
causes the spin.
Something about this situation causes pthread_exit to segfault
when DVBSubtitles->threadStop() is called.

Also fixed missing else brackets in cTimeMs constructor.
---
 dvbsubtitles.cc | 7 +++++++
 dvbsubtitles.h  | 1 +
 2 files changed, 8 insertions(+)

diff --git a/dvbsubtitles.cc b/dvbsubtitles.cc
index 316e403..5351b6f 100644
--- a/dvbsubtitles.cc
+++ b/dvbsubtitles.cc
@@ -37,11 +37,15 @@
 
 cTimeMs::cTimeMs(int Ms)
 {
+  initted = false;
+
   if (Ms >= 0)
      Set(Ms);
   else
+  {
      begin = 0;
      isFirstCheck = false;
+  }
 }
 
 uint64_t cTimeMs::Now(void)
@@ -59,6 +63,8 @@ void cTimeMs::Set(int Ms)
 {
   isFirstCheck = true; // Timer set, the first check can be done once
   begin = Now() + Ms;
+
+  if (Ms) initted = true;
 }
 
 bool cTimeMs::TimedOut(void)
@@ -74,6 +80,7 @@ bool cTimeMs::TimedOut(void)
 
 uint64_t cTimeMs::Elapsed(void)
 {
+  if (!initted) return 0;
   return Now() - begin;
 }
 
diff --git a/dvbsubtitles.h b/dvbsubtitles.h
index 701bf9e..d268169 100644
--- a/dvbsubtitles.h
+++ b/dvbsubtitles.h
@@ -48,6 +48,7 @@ class cTimeMs {
     void Set(int Ms = 0);
     bool TimedOut(void);
     uint64_t Elapsed(void);
+    bool initted;
 };
 
 class OSDReceiver;
-- 
2.39.5