[FFmpeg-devel] [PATCH] hevc_mvs: set candidate availabilities

[Christophe Gisquet]

The patch fixes overreads (and crashes) introduced in 3ad04608.

-- 
Christophe

From adfac6472b015e162988e2e2208e95cc87248be2 Mon Sep 17 00:00:00 2001
From: Christophe Gisquet <christophe.gisq...@gmail.com>
Date: Sun, 10 Aug 2014 15:02:36 +0200
Subject: [PATCH] hevc_mvs: set candidate availabilities

They might be left uninitialized otherwise since 3ad04608.

Fixes ticket #3840.

Found-by: Carl Eugen Hoyos <c...@hoyos.ws>
Reported-by: Piotr Bandurski <ami_st...@o2.pl>
---
 libavcodec/hevc_mvs.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/libavcodec/hevc_mvs.c b/libavcodec/hevc_mvs.c
index 4564d71..a144ded 100644
--- a/libavcodec/hevc_mvs.c
+++ b/libavcodec/hevc_mvs.c
@@ -677,6 +677,17 @@ b_candidates:
                        xB0 < s->sps->width &&
                        PRED_BLOCK_AVAILABLE(B0);
 
+    // above spatial merge candidate
+    xB1    = x0 + nPbW - 1;
+    yB1    = y0 - 1;
+    is_available_b1 = AVAILABLE(cand_up, B1);
+
+    // above left spatial merge candidate
+    xB2 = x0 - 1;
+    yB2 = y0 - 1;
+    is_available_b2 = AVAILABLE(cand_up_left, B2);
+
+    // above right spatial merge candidate
     if (is_available_b0) {
         if (MP_MX(B0, pred_flag_index_l0, mxB)) {
             goto scalef;
@@ -687,11 +698,6 @@ b_candidates:
     }
 
     // above spatial merge candidate
-    xB1    = x0 + nPbW - 1;
-    yB1    = y0 - 1;
-
-    is_available_b1 = AVAILABLE(cand_up, B1);
-
     if (is_available_b1) {
         if (MP_MX(B1, pred_flag_index_l0, mxB)) {
             goto scalef;
@@ -702,10 +708,6 @@ b_candidates:
     }
 
     // above left spatial merge candidate
-    xB2 = x0 - 1;
-    yB2 = y0 - 1;
-    is_available_b2 = AVAILABLE(cand_up_left, B2);
-
     if (is_available_b2) {
         if (MP_MX(B2, pred_flag_index_l0, mxB)) {
             goto scalef;
-- 
1.9.2.msysgit.0


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