[FFmpeg-devel] [PATCH v2 1/2] avformat/url: check double dot is not to parent directory

[Steven Liu]

Nicolas George <george at nsup.org> 于2020年7月25日周六 下午4:31写道：
>
> Steven Liu (12020-07-25):
> > fix ticket: 8814
> > if get ".." in the url, check next byte and lead byte by double dot,
> > it there have no '/' and not root node, it is not used go to directory ".."
> >
> > Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
> > ---
> >  libavformat/url.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/libavformat/url.c b/libavformat/url.c
> > index 20463a6674..35f27fe3ca 100644
> > --- a/libavformat/url.c
> > +++ b/libavformat/url.c
> > @@ -97,6 +97,18 @@ static void trim_double_dot_url(char *buf, const char *rel, int size)
> >      /* set new current position if the root node is changed */
> >      p = root;
> >      while (p && (node = strstr(p, ".."))) {
>
> > +        if (strlen(node) > 2 && node[2] != '/') {
>
> I have not yet looked at the whole patch, but this strlen() test is
> useless.
>
> And I think you would better rework the complete logic of the test:
agreed, I think need lots of testcase for the logic, ../ .../..
dummy../... .../..dummy and so on,
maybe need spend some time to do it :D
> strstring ".." is a broken method.
>
> > +            node = strstr(node + 1, "..");
> > +            if (!node)
> > +                break;
> > +        }
> > +
> > +        if (p != node && p[node - p - 1] != '/') {
> > +            node = strstr(node + 1, "..");
> > +            if (!node)
> > +                break;
> > +        }
> > +
> >          av_strlcat(tmp_path, p, node - p + strlen(tmp_path));
> >          p = node + 3;
> >          sep = strrchr(tmp_path, '/');
>
> Regards,
>
> --
>   Nicolas George
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