[FFmpeg-devel] [PATCH] Avoid undefined behavior by limiting PTS to 62 bits in ogg decoder

[Fredrik Hubinette]

With some (garbled) OGG data, PTS can overflow causing undefined behavior.
This patch avoids that by zeroing out PTS values greater than 2^62.

From 26a8582bc04f5bddc037ffcce99025e2f977abe0 Mon Sep 17 00:00:00 2001
From: Fredrik Hubinette <hu...@google.com>
Date: Mon, 16 Jul 2018 14:54:43 -0700
Subject: [PATCH] Avoid undefined behavior by limiting PTS to 62 bits in ogg
 decoder

---
 libavformat/oggdec.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavformat/oggdec.h b/libavformat/oggdec.h
index 4a2b6ddee8..798c74f671 100644
--- a/libavformat/oggdec.h
+++ b/libavformat/oggdec.h
@@ -162,8 +162,9 @@ ogg_gptopts (AVFormatContext * s, int i, uint64_t gp, int64_t *dts)
         if (dts)
             *dts = pts;
     }
-    if (pts > INT64_MAX && pts != AV_NOPTS_VALUE) {
+    if (pts > INT64_MAX / 2 && pts != AV_NOPTS_VALUE) {
         // The return type is unsigned, we thus cannot return negative pts
+        // Limit the return value to 62 bits to avoid undefined behavior.
         av_log(s, AV_LOG_ERROR, "invalid pts %"PRId64"\n", pts);
         pts = AV_NOPTS_VALUE;
     }
-- 
2.18.0.203.gfac676dfb9-goog


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