[FFmpeg-cvslog] avcodec/vbn(dec|enc): Avoid leaving stale pointers in context

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Tue Apr 12 19:17:08 2022 +0200| [300dd79c3d764a5d38b914bb0f36ba195422068e] | committer: Andreas Rheinhardt

avcodec/vbn(dec|enc): Avoid leaving stale pointers in context

Therefore move the (Get|Put)ByteContext from the context to the stack.
It is transient anyway.

Reviewed-by: Marton Balint <cus at passwd.hu>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=300dd79c3d764a5d38b914bb0f36ba195422068e
---

 libavcodec/vbndec.c | 11 ++++-------
 libavcodec/vbnenc.c |  3 +--
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/libavcodec/vbndec.c b/libavcodec/vbndec.c
index 916421925d..56bfb1d544 100644
--- a/libavcodec/vbndec.c
+++ b/libavcodec/vbndec.c
@@ -34,7 +34,6 @@
 typedef struct VBNContext {
     TextureDSPContext texdsp;
     TextureDSPThreadContext dec;
-    GetByteContext gb;
 } VBNContext;
 
 static av_cold int vbn_init(AVCodecContext *avctx)
@@ -44,11 +43,9 @@ static av_cold int vbn_init(AVCodecContext *avctx)
     return 0;
 }
 
-static int decompress(AVCodecContext *avctx, int compression, uint8_t **outbuf)
+static int decompress(AVCodecContext *avctx, GetByteContext *gb,
+                      int compression, uint8_t **outbuf)
 {
-    VBNContext *ctx = avctx->priv_data;
-    GetByteContext *gb = &ctx->gb;
-
     if (compression == VBN_COMPRESSION_NONE) // outbuf is left NULL because gb->buf can be used directly
         return bytestream2_get_bytes_left(gb);
 
@@ -61,7 +58,7 @@ static int vbn_decode_frame(AVCodecContext *avctx,
                             AVPacket *avpkt)
 {
     VBNContext *ctx    = avctx->priv_data;
-    GetByteContext *gb = &ctx->gb;
+    GetByteContext gb0, *const gb = &gb0;
     uint8_t *image_buf = NULL;
     int      image_len;
     int width, height, components, format, compression, pix_fmt, linesize, data_size;
@@ -139,7 +136,7 @@ static int vbn_decode_frame(AVCodecContext *avctx,
         return AVERROR_PATCHWELCOME;
     }
 
-    image_len = decompress(avctx, compression, &image_buf);
+    image_len = decompress(avctx, gb, compression, &image_buf);
     if (image_len < 0)
         return image_len;
 
diff --git a/libavcodec/vbnenc.c b/libavcodec/vbnenc.c
index 0b2c4dced2..03d36ccc86 100644
--- a/libavcodec/vbnenc.c
+++ b/libavcodec/vbnenc.c
@@ -37,7 +37,6 @@
 typedef struct VBNContext {
     AVClass *class;
     TextureDSPContext dxtc;
-    PutByteContext pb;
     int format;
     TextureDSPThreadContext enc;
 } VBNContext;
@@ -46,7 +45,7 @@ static int vbn_encode(AVCodecContext *avctx, AVPacket *pkt,
                       const AVFrame *frame, int *got_packet)
 {
     VBNContext *ctx = avctx->priv_data;
-    PutByteContext *pb = &ctx->pb;
+    PutByteContext pb0, *const pb = &pb0;
     int ret;
     ptrdiff_t linesize;
     int64_t pkt_size;