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

[Michael Niedermayer]

On Tue, Feb 14, 2017 at 09:39:08AM +0800, Steven Liu wrote:
> 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
> >
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> 
> 
> LGTM,

applied


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

it would result in warnings of being unneeded in some tools probably

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The misfortune of the wise is better than the prosperity of the fool.
-- Epicurus
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