On Thu, Jul 26, 2018 at 10:07:34AM -0700, Darrick J. Wong wrote:
> On Thu, Jul 26, 2018 at 11:40:46AM -0500, Bill O'Donnell wrote:
> > 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>
> > ---
> >
> > v4: adjust control flow to standard error checking. Add
> > more descriptive comment. Add validation for sb_icount.
> > v3: eliminate need for additional write_flag, doing those
> > unique checks in xfs_sb_write_verify()
> > v2: make extra sanity checks exclusive to writes
> >
> > fs/xfs/libxfs/xfs_sb.c | 46 +++++++++++++++++++++++++++++++++---------
> > 1 file changed, 36 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> > index b3ad15956366..8d8e579ca426 100644
> > --- a/fs/xfs/libxfs/xfs_sb.c
> > +++ b/fs/xfs/libxfs/xfs_sb.c
> > @@ -599,22 +599,16 @@ xfs_sb_to_disk(
> > static int
> > xfs_sb_verify(
> > struct xfs_buf *bp,
> > + struct xfs_sb *sb,
> > bool check_version)
> > {
> > struct xfs_mount *mp = bp->b_target->bt_mount;
> > - struct xfs_sb sb;
> > -
> > - /*
> > - * Use call variant which doesn't convert quota flags from disk
> > - * format, because xfs_mount_validate_sb checks the on-disk flags.
> > - */
> > - __xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);
> >
> > /*
> > * Only check the in progress field for the primary superblock as
> > * mkfs.xfs doesn't clear it from secondary superblocks.
> > */
> > - return xfs_mount_validate_sb(mp, &sb,
> > + return xfs_mount_validate_sb(mp, sb,
> > bp->b_maps[0].bm_bn == XFS_SB_DADDR,
> > check_version);
> > }
> > @@ -637,6 +631,7 @@ xfs_sb_read_verify(
> > {
> > struct xfs_mount *mp = bp->b_target->bt_mount;
> > struct xfs_dsb *dsb = XFS_BUF_TO_SBP(bp);
> > + struct xfs_sb sb;
> > int error;
> >
> > /*
> > @@ -657,7 +652,13 @@ xfs_sb_read_verify(
> > }
> > }
> > }
> > - error = xfs_sb_verify(bp, true);
> > +
> > + /*
> > + * Use call variant which doesn't convert quota flags from disk
> > + * format, because xfs_mount_validate_sb checks the on-disk flags.
> > + */
> > + __xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);
> > + error = xfs_sb_verify(bp, &sb, true);
> >
> > out_error:
> > if (error == -EFSCORRUPTED || error == -EFSBADCRC)
> > @@ -693,9 +694,34 @@ xfs_sb_write_verify(
> > {
> > struct xfs_mount *mp = bp->b_target->bt_mount;
> > struct xfs_buf_log_item *bip = bp->b_log_item;
> > + struct xfs_sb sb;
> > int error;
> >
> > - error = xfs_sb_verify(bp, false);
> > + /*
> > + * Use call variant which doesn't convert quota flags from disk
> > + * format, because xfs_mount_validate_sb checks the on-disk flags.
> > + */
> > + __xfs_sb_from_disk(&sb, XFS_BUF_TO_SBP(bp), false);
> > +
> > + error = xfs_sb_verify(bp, &sb, false);
> > + if (error)
> > + goto err;
> > +
> > + /*
> > + * Carry out additional sb sanity checks exclusively for writes.
> > + * We don't do these checks for reads, since faulty parameters could
> > + * already be on disk, and we shouldn't preclude reads for those
> > + * cases.
> > + */
> > + if (sb.sb_fdblocks > sb.sb_dblocks ||
> > + sb.sb_icount / sb.sb_inopblock > sb.sb_dblocks ||
>
> This is a 64-bit division, which won't work on 32-bit builds.
>
> That said, I also wrote a xfs_verify_icount function for the fs summary
> scrub patch, so perhaps we should collaborate to land both of these?
> Send a v5 without this test and I'll immediately send a patch adding
> both the _verify_icount and putting it to use here.
>
> Actually, I could just modify your patch, add mine, and send both of
> them. That'd be easier...
That sounds fine. Thanks!
Bill
>
> --D
>
> > + sb.sb_ifree > sb.sb_icount) {
> > + xfs_notice(mp, "SB sanity check failed");
> > + error = -EFSCORRUPTED;
> > + goto err;
> > + }
> > +
> > +err:
> > if (error) {
> > xfs_verifier_error(bp, error, __this_address);
> > return;
> > --
> > 2.17.1
> >
> > --
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