Re: [FFmpeg-devel] [PATCH] avformat/mov: Don't allocate unnecessarily large blocks of memory

["\"zhilizhao(赵志立)\"" <quinkblack@foxmail.com>]

> On Jun 9, 2023, at 07:51, Hendi <finalcountdown72@googlemail.com> wrote:
> 
> mov_try_read_block is regularly called with sizes such as 48 bytes,
> but would allocate 1 MiB each time, hogging more and more memory
> until playback ends.
> 
> Fixes #7641 and #9243.

It’s a quick fix, but I’m afraid the two tickets are caused by more deep
pitfalls.

It would be helpful if someone can provide a sample for test.

> 
> Signed-off-by: Hendi <hendi48@freenet.de>
> ---
> libavformat/mov.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index a8d004e02b..2e4df42256 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -6662,6 +6662,9 @@ static int mov_try_read_block(AVIOContext *pb, size_t size, uint8_t **data)
>     while (offset < size) {
>         unsigned int new_size =
>             alloc_size >= INT_MAX - block_size ? INT_MAX : alloc_size + block_size;
> +        if (size < new_size) {
> +            new_size = size;
> +        }
>         uint8_t *new_buffer = av_fast_realloc(buffer, &alloc_size, new_size);
>         unsigned int to_read = FFMIN(size, alloc_size) - offset;
>         if (!new_buffer) {
> -- 
> 2.40.0.windows.1
> 
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