On Mon, Jul 30, 2018 at 06:16:40PM -0500, Eric Sandeen wrote:
> On 7/30/18 12:30 AM, Darrick J. Wong wrote:
> > From: Bill O'Donnell <billodo@xxxxxxxxxx>
> >
> > Current sb verifier doesn't check bounds on sb_fdblocks and sb_ifree.
> > Add sanity checks for these parameters.
> >
> > Signed-off-by: Bill O'Donnell <billodo@xxxxxxxxxx>
> > [darrick: port to refactored sb validation predicates]
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> comment nitpicks below, but otherwise
>
> Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>
> > ---
> > fs/xfs/libxfs/xfs_sb.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> >
> > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> > index 516bef7b0f50..64bc471d57e6 100644
> > --- a/fs/xfs/libxfs/xfs_sb.c
> > +++ b/fs/xfs/libxfs/xfs_sb.c
> > @@ -153,6 +153,18 @@ xfs_validate_sb_write(
> > struct xfs_mount *mp,
> > struct xfs_sb *sbp)
> > {
> > + /*
> > + * Carry out additional sb sanity checks exclusively for writes.
>
> We're in xfs_validate_sb_write so that's obvious, can drop this line.
>
> > + * We don't do these checks for reads, since faulty parameters could
> > + * be fixed in the log, and we shouldn't prohibit mounting for those
> > + * cases.
> > + */
>
> Hm, it's not really a log reaplay issue, right? These summary counters
> get reinitialized at mount, so failing to mount before we overwrite them
> anyway makes no sense.
Well, we don't reinitialize them if ( (!lazysbcount) or (clean log) )
and (non-crazy values)...
> /*
> * These summary counters get re-initialized after they are read
> * during mount, so this is a write-only check.
They're not always re-initialized -- only if we had a dirty lazysbcont
fs or the values were crazy.
/*
* Carry out additional sb summary counter sanity checks when we write
* the superblock. We skip this in the read validator because there
* could be newer superblocks in the log and if the values are garbage
* even after replay we'll recalculate them at the end of log mount.
*/
--D
> */
>
> ? And yeah, modulo lazycount... but whatevs.
>
> -Eric
>
> > + if (sbp->sb_fdblocks > sbp->sb_dblocks ||
> > + sbp->sb_ifree > sbp->sb_icount) {
> > + xfs_warn(mp, "SB summary counter sanity check failed");
> > + return -EFSCORRUPTED;
> > + }
> > +
> > if (!xfs_sb_version_hascrc(sbp))
> > return 0;
> --
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