On Fri, Sep 7, 2018 at 2:54 PM Guenter Roeck <groeck@xxxxxxxxxx> wrote: > > On Fri, Sep 7, 2018 at 2:34 PM Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > 4.9-stable review patch. If anyone has any objections, please let me know. > > > > Do your scripts have a bad hair day ? The subject says 4.18. > Hmm, I suspect it is the gmail UI messing with me. Sorry for the noise. Guenter > Guenter > > > ------------------ > > > > From: Chirantan Ekbote <chirantan@xxxxxxxxxxxx> > > > > commit d28c756caee6e414d9ba367d0b92da24145af2a8 upstream. > > > > The zero-copy optimization when reading or writing large chunks of data > > is quite useful. However, the 9p messages created through the zero-copy > > write path have an incorrect message size: it should be the size of the > > header + size of the data being written but instead it's just the size > > of the header. > > > > This only works if the server ignores the size field of the message and > > otherwise breaks the framing of the protocol. Fix this by re-writing the > > message size field with the correct value. > > > > Tested by running `dd if=/dev/zero of=out bs=4k count=1` inside a > > virtio-9p mount. > > > > Link: http://lkml.kernel.org/r/20180717003529.114368-1-chirantan@xxxxxxxxxxxx > > Signed-off-by: Chirantan Ekbote <chirantan@xxxxxxxxxxxx> > > Reviewed-by: Greg Kurz <groug@xxxxxxxx> > > Tested-by: Greg Kurz <groug@xxxxxxxx> > > Cc: Dylan Reid <dgreid@xxxxxxxxxxxx> > > Cc: Guenter Roeck <groeck@xxxxxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxx> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > > --- > > net/9p/trans_virtio.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > --- a/net/9p/trans_virtio.c > > +++ b/net/9p/trans_virtio.c > > @@ -406,6 +406,7 @@ p9_virtio_zc_request(struct p9_client *c > > p9_debug(P9_DEBUG_TRANS, "virtio request\n"); > > > > if (uodata) { > > + __le32 sz; > > int n = p9_get_mapped_pages(chan, &out_pages, uodata, > > outlen, &offs, &need_drop); > > if (n < 0) > > @@ -416,6 +417,12 @@ p9_virtio_zc_request(struct p9_client *c > > memcpy(&req->tc->sdata[req->tc->size - 4], &v, 4); > > outlen = n; > > } > > + /* The size field of the message must include the length of the > > + * header and the length of the data. We didn't actually know > > + * the length of the data until this point so add it in now. > > + */ > > + sz = cpu_to_le32(req->tc->size + outlen); > > + memcpy(&req->tc->sdata[0], &sz, sizeof(sz)); > > } else if (uidata) { > > int n = p9_get_mapped_pages(chan, &in_pages, uidata, > > inlen, &offs, &need_drop); > > > >
