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xfs: forbid AG btrees with level == 0

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There is no such thing as a zero-level AG btree since even a single-node
zero-records btree has one level.  Btree cursor constructors read
cur_nlevels straight from disk and then access things like
cur_bufs[cur_nlevels - 1] which is /really/ bad if cur_nlevels is zero!
Therefore, strengthen the verifiers to prevent this possibility.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Darrick J. Wong 2016-12-05 12:32:50 +11:00 committed by Dave Chinner
parent f7a136aee3
commit d2a047f31e
2 changed files with 15 additions and 4 deletions
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10
fs/xfs/libxfs/xfs_alloc.c
View File

@ -2455,12 +2455,15 @@ xfs_agf_verify(
be32_to_cpu(agf->agf_flcount) <= XFS_AGFL_SIZE(mp)))
return false;
if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) > XFS_BTREE_MAXLEVELS ||
if (be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) < 1 ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) < 1 ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_BNO]) > XFS_BTREE_MAXLEVELS ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_CNT]) > XFS_BTREE_MAXLEVELS)
return false;
if (xfs_sb_version_hasrmapbt(&mp->m_sb) &&
be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS)
(be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) < 1 ||
be32_to_cpu(agf->agf_levels[XFS_BTNUM_RMAP]) > XFS_BTREE_MAXLEVELS))
return false;
/*
@ -2477,7 +2480,8 @@ xfs_agf_verify(
return false;
if (xfs_sb_version_hasreflink(&mp->m_sb) &&
be32_to_cpu(agf->agf_refcount_level) > XFS_BTREE_MAXLEVELS)
(be32_to_cpu(agf->agf_refcount_level) < 1 ||
be32_to_cpu(agf->agf_refcount_level) > XFS_BTREE_MAXLEVELS))
return false;
return true;;

9
fs/xfs/libxfs/xfs_ialloc.c
View File

@ -2510,8 +2510,15 @@ xfs_agi_verify(
if (!XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum)))
return false;
if (be32_to_cpu(agi->agi_level) > XFS_BTREE_MAXLEVELS)
if (be32_to_cpu(agi->agi_level) < 1 ||
be32_to_cpu(agi->agi_level) > XFS_BTREE_MAXLEVELS)
return false;
if (xfs_sb_version_hasfinobt(&mp->m_sb) &&
(be32_to_cpu(agi->agi_free_level) < 1 ||
be32_to_cpu(agi->agi_free_level) > XFS_BTREE_MAXLEVELS))
return false;
/*
* during growfs operations, the perag is not fully initialised,
* so we can't use it for any useful checking. growfs ensures we can't