From b96ba62bddd1e06f42bad1407455834b19686e32 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Thu, 5 Oct 2023 23:16:44 +0200
Subject: [PATCH] avcodec/mpegvideo_enc: Fix abort on allocation errors

mpegvideo_enc uses a fixed-size array of Pictures; a slot is
considered taken if the Picture's AVFrame is set.
When an error happens after a slot has been taken, this Picture
has typically not been reset and is therefore not usable for
future requests. The code aborts when one runs out of slots
and this can happen in case of allocation failures.
Fix this by always unreferencing a Picture in case of errors.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/mpegvideo_enc.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
index f669658127..bc89de0550 100644
--- a/libavcodec/mpegvideo_enc.c
+++ b/libavcodec/mpegvideo_enc.c
@@ -1224,8 +1224,10 @@ static int load_input_picture(MpegEncContext *s, const AVFrame *pic_arg)
             }
         }
         ret = av_frame_copy_props(pic->f, pic_arg);
-        if (ret < 0)
+        if (ret < 0) {
+            ff_mpeg_unref_picture(s->avctx, pic);
             return ret;
+        }
 
         pic->display_picture_number = display_picture_number;
         pic->f->pts = pts; // we set this here to avoid modifying pic_arg
@@ -1536,8 +1538,10 @@ static int select_input_picture(MpegEncContext *s)
                 }
             } else if (s->b_frame_strategy == 2) {
                 b_frames = estimate_best_b_count(s);
-                if (b_frames < 0)
+                if (b_frames < 0) {
+                    ff_mpeg_unref_picture(s->avctx, s->input_picture[0]);
                     return b_frames;
+                }
             }
 
             emms_c();
@@ -1592,7 +1596,7 @@ no_output_pic:
 
         if ((ret = av_frame_ref(s->new_picture,
                                 s->reordered_input_picture[0]->f)))
-            return ret;
+            goto fail;
 
         if (s->reordered_input_picture[0]->shared || s->avctx->rc_buffer_size) {
             // input is a shared pix, so we can't modify it -> allocate a new
@@ -1605,13 +1609,15 @@ no_output_pic:
             pic = &s->picture[i];
 
             pic->reference = s->reordered_input_picture[0]->reference;
-            if (alloc_picture(s, pic, 0) < 0) {
-                return -1;
-            }
+            ret = alloc_picture(s, pic, 0);
+            if (ret < 0)
+                goto fail;
 
             ret = av_frame_copy_props(pic->f, s->reordered_input_picture[0]->f);
-            if (ret < 0)
-                return ret;
+            if (ret < 0) {
+                ff_mpeg_unref_picture(s->avctx, pic);
+                goto fail;
+            }
             pic->coded_picture_number = s->reordered_input_picture[0]->coded_picture_number;
             pic->display_picture_number = s->reordered_input_picture[0]->display_picture_number;
 
@@ -1632,6 +1638,9 @@ no_output_pic:
 
     }
     return 0;
+fail:
+    ff_mpeg_unref_picture(s->avctx, s->reordered_input_picture[0]);
+    return ret;
 }
 
 static void frame_end(MpegEncContext *s)