On Mon, Jan 07, 2019 at 09:52:29AM -0800, Darrick J. Wong wrote: > On Mon, Jan 07, 2019 at 04:53:10AM -0500, Su Yanjun wrote: > > For statx syscall, xfs return the wrong result_mask. > > > > Signed-off-by: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx> > > --- > > fs/xfs/xfs_iops.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > > index f48ffd7..3811457 100644 > > --- a/fs/xfs/xfs_iops.c > > +++ b/fs/xfs/xfs_iops.c > > @@ -521,6 +521,9 @@ xfs_vn_getattr( > > stat->btime.tv_nsec = ip->i_d.di_crtime.t_nsec; > > } > > } > > + > > + /* Only return mask that we care */ > > + stat->result_mask &= request_mask; > > Why not just: > > stat->result_mask = STATX_BASIC_STATS; > > at the top of the function? > > I don't see the need to mask off result_mask at all, since we could some > day elect to return more than what's in request_mask... > > ...waitaminute, are you seeing garbage in the result_mask that's > returned to userspace? I also noticed the vfs stat functions declare > "struct kstat stat;" without explicitly zeroing the structure fields, > which means (I think) that we can leak stack information if the kernel > isn't built with the stackleak plugin? Ignore the above; vfs_getattr_nosec actually does zero the kstat buffer before calling ->getattr. We also set result_mask to STATX_BASIC_STATS. Now I'm really confused: why is this necessary at all? What incorrect masks did you see, and under what circumstances? --D > --D > > > > > if (ip->i_d.di_flags & XFS_DIFLAG_IMMUTABLE) > > stat->attributes |= STATX_ATTR_IMMUTABLE; > > -- > > 2.7.4 > > > > > >
