[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v4 03/11] 9pfs: validate count sent by client with T_readdir
From: |
Christian Schoenebeck |
Subject: |
Re: [PATCH v4 03/11] 9pfs: validate count sent by client with T_readdir |
Date: |
Wed, 22 Jan 2020 15:26:13 +0100 |
On Mittwoch, 22. Januar 2020 15:11:07 CET Greg Kurz wrote:
> On Tue, 21 Jan 2020 00:50:33 +0100
>
> Christian Schoenebeck <address@hidden> wrote:
> > A good 9p client sends T_readdir with "count" parameter that's
> > sufficiently
> > smaller than client's initially negotiated msize (maximum message size).
> > We perform a check for that though to avoid the server to be interrupted
> > with a "Failed to encode VirtFS reply type 41" transport error message by
> > bad clients. This count value constraint uses msize - 11, because 11 is
> > the
> > header size of R_readdir.
>
> This would be worth a comment...
>
> > Signed-off-by: Christian Schoenebeck <address@hidden>
> > ---
> >
> > hw/9pfs/9p.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > index a5fbe821d4..18370183c4 100644
> > --- a/hw/9pfs/9p.c
> > +++ b/hw/9pfs/9p.c
> > @@ -2426,6 +2426,7 @@ static void coroutine_fn v9fs_readdir(void *opaque)
> >
> > int32_t count;
> > uint32_t max_count;
> > V9fsPDU *pdu = opaque;
> >
> > + V9fsState *s = pdu->s;
> >
> > retval = pdu_unmarshal(pdu, offset, "dqd", &fid,
> >
> > &initial_offset, &max_count);
> >
> > @@ -2434,6 +2435,13 @@ static void coroutine_fn v9fs_readdir(void *opaque)
> >
> > }
> > trace_v9fs_readdir(pdu->tag, pdu->id, fid, initial_offset,
> > max_count);
>
> ... here. Something like:
>
> /* Enough space for a R_readdir header: size[4] Rreaddir tag[2] count[4]
> */
>
> I can fix this in my tree, and actually done so since I've
> applied patches 1 to 3.
Fine with me, thanks Greg!
> Reviewed-by: Greg Kurz <address@hidden>
Best regards,
Christian Schoenebeck
- [PATCH v4 06/11] tests/virtio-9p: added splitted readdir test, (continued)
[PATCH v4 03/11] 9pfs: validate count sent by client with T_readdir, Christian Schoenebeck, 2020/01/20
[PATCH v4 08/11] 9pfs: readdir benchmark, Christian Schoenebeck, 2020/01/20