[FFmpeg-devel] [PATCH] avformat/http: Check for truncated buffers in http_connect()

[Steven Liu]

2017-02-13 20:46 GMT+08:00 Michael Niedermayer <michael at niedermayer.cc>:

> Reported-by: SleepProgger <security at gnutp.com>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/http.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/http.c b/libavformat/http.c
> index 944a6cf322..bd1be3f7bb 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -1011,6 +1011,7 @@ static int http_connect(URLContext *h, const char
> *path, const char *local_path,
>      int len = 0;
>      const char *method;
>      int send_expect_100 = 0;
> +    int ret;
>
>      /* send http header */
>      post = h->flags & AVIO_FLAG_WRITE;
> @@ -1107,7 +1108,7 @@ static int http_connect(URLContext *h, const char
> *path, const char *local_path,
>      if (s->headers)
>          av_strlcpy(headers + len, s->headers, sizeof(headers) - len);
>
> -    snprintf(s->buffer, sizeof(s->buffer),
> +    ret = snprintf(s->buffer, sizeof(s->buffer),
>               "%s %s HTTP/1.1\r\n"
>               "%s"
>               "%s"
> @@ -1123,6 +1124,14 @@ static int http_connect(URLContext *h, const char
> *path, const char *local_path,
>
>      av_log(h, AV_LOG_DEBUG, "request: %s\n", s->buffer);
>
> +    if (strlen(headers) + 1 == sizeof(headers) ||
> +        ret >= sizeof(s->buffer)) {
> +        av_log(h, AV_LOG_ERROR, "overlong headers\n");
> +        err = AVERROR(EINVAL);
> +        goto done;
> +    }
> +
> +
>      if ((err = ffurl_write(s->hd, s->buffer, strlen(s->buffer))) < 0)
>          goto done;
>
> --
> 2.11.0
>
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LGTM,

BTW, what about give a initial value 0 when define the ‘ret’ variable?


Thanks