The earlier code would first attempt to allocate two buffers, then
attempt to allocate an AVIOContext, using one of the new buffers I/O
buffer, then check the allocations. On success, a z_stream that is used
in the AVIOContext's read_packet callback is initialized afterwards.
There are two problems with this: In case the allocation of the I/O
buffer fails avio_alloc_context() will be given a NULL read buffer
with a size > 0. This works right now, but it is fragile. The second
problem is that the z_stream used in the read_packet callback is not
functional when avio_alloc_context() is allocated (it might be that
avio_alloc_context() might already fill the buffer in the future). This
commit fixes both of these problems by reordering the operations.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
libavformat/swfdec.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)
diff --git a/libavformat/swfdec.c b/libavformat/swfdec.c
index 7a74fa3ac7..d1ed1e2a53 100644
--- a/libavformat/swfdec.c
+++ b/libavformat/swfdec.c
@@ -128,6 +128,8 @@ retry:
return buf_size - z->avail_out;
}
+
+static av_cold int swf_read_close(AVFormatContext *avctx);
#endif
static int swf_read_header(AVFormatContext *s)
@@ -142,24 +144,18 @@ static int swf_read_header(AVFormatContext *s)
if (tag == MKBETAG('C', 'W', 'S', 0)) {
av_log(s, AV_LOG_INFO, "SWF compressed file detected\n");
#if CONFIG_ZLIB
- swf->zbuf_in = av_malloc(ZBUF_SIZE);
- swf->zbuf_out = av_malloc(ZBUF_SIZE);
- swf->zpb = avio_alloc_context(swf->zbuf_out, ZBUF_SIZE, 0, s,
- zlib_refill, NULL, NULL);
- if (!swf->zbuf_in || !swf->zbuf_out || !swf->zpb) {
- av_freep(&swf->zbuf_in);
- av_freep(&swf->zbuf_out);
- avio_context_free(&swf->zpb);
- return AVERROR(ENOMEM);
- }
- swf->zpb->seekable = 0;
if (inflateInit(&swf->zstream) != Z_OK) {
av_log(s, AV_LOG_ERROR, "Unable to init zlib context\n");
- av_freep(&swf->zbuf_in);
- av_freep(&swf->zbuf_out);
- avio_context_free(&swf->zpb);
return AVERROR(EINVAL);
}
+ if (!(swf->zbuf_in = av_malloc(ZBUF_SIZE)) ||
+ !(swf->zbuf_out = av_malloc(ZBUF_SIZE)) ||
+ !(swf->zpb = avio_alloc_context(swf->zbuf_out, ZBUF_SIZE, 0,
+ s, zlib_refill, NULL, NULL))) {
+ swf_read_close(s);
+ return AVERROR(ENOMEM);
+ }
+ swf->zpb->seekable = 0;
pb = swf->zpb;
#else
av_log(s, AV_LOG_ERROR, "zlib support is required to read SWF
compressed files\n");
--
2.25.1
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