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...
--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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