Andreas Rheinhardt:
> 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");
>
Will apply.
- Andreas
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