ACK/Cmnt: [SRU][F][G][PATCH 1/1] ceph: fix endianness bug when handling MDS session feature bits

[Frank Heimes]

Sorry, forgot to copy over the SRU justification to the bug description.
Did it now ...


On Wed, May 13, 2020 at 2:23 PM Stefan Bader <stefan.bader at canonical.com>
wrote:

> On 11.05.20 11:02, frank.heimes at canonical.com wrote:
> > From: Jeff Layton <jlayton at kernel.org>
> >
> > BugLink: https://bugs.launchpad.net/bugs/1875863
> >
> > Eduard reported a problem mounting cephfs on s390 arch. The feature
> > mask sent by the MDS is little-endian, so we need to convert it
> > before storing and testing against it.
> >
> > Cc: stable at vger.kernel.org
> > Reported-and-Tested-by: Eduard Shishkin <edward6 at linux.ibm.com>
> > Signed-off-by: Jeff Layton <jlayton at kernel.org>
> > Reviewed-by: "Yan, Zheng" <zyan at redhat.com>
> > Signed-off-by: Ilya Dryomov <idryomov at gmail.com>
> > (cherry picked from commit 0fa8263367db9287aa0632f96c1a5f93cc478150)
> > Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> Acked-by: Stefan Bader <stefan.bader at canonical.com>
> > ---
>
> SRU justification should be in the bug reports description so the
> Launchpad SRU
> team (archive admins) have a chance to read it.
>
> -Stefan
>
> >  fs/ceph/mds_client.c | 8 +++-----
> >  1 file changed, 3 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> > index 8c1f04c3a684..b79fe6549df6 100644
> > --- a/fs/ceph/mds_client.c
> > +++ b/fs/ceph/mds_client.c
> > @@ -3072,8 +3072,7 @@ static void handle_session(struct ceph_mds_session
> *session,
> >       void *end = p + msg->front.iov_len;
> >       struct ceph_mds_session_head *h;
> >       u32 op;
> > -     u64 seq;
> > -     unsigned long features = 0;
> > +     u64 seq, features = 0;
> >       int wake = 0;
> >       bool blacklisted = false;
> >
> > @@ -3092,9 +3091,8 @@ static void handle_session(struct ceph_mds_session
> *session,
> >                       goto bad;
> >               /* version >= 3, feature bits */
> >               ceph_decode_32_safe(&p, end, len, bad);
> > -             ceph_decode_need(&p, end, len, bad);
> > -             memcpy(&features, p, min_t(size_t, len, sizeof(features)));
> > -             p += len;
> > +             ceph_decode_64_safe(&p, end, features, bad);
> > +             p += len - sizeof(features);
> >       }
> >
> >       mutex_lock(&mdsc->mutex);
> >
>
>
> --
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