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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-27 02:06:01 +0200 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-08-28 17:31:01 +0200 |
| commit | c94613feefd7714ad0d03a1914632c15782114ff (patch) | |
| tree | 676294a5dc3f20960df163bac47005ddf91d0c31 | |
| parent | xfs: bmap scrub should only scrub records once (diff) | |
| download | linux-c94613feefd7714ad0d03a1914632c15782114ff.tar.xz linux-c94613feefd7714ad0d03a1914632c15782114ff.zip | |
xfs: fix maxicount division by zero error
In xfs_ialloc_setup_geometry, it's possible for a malicious/corrupt fs
image to set an unreasonably large value for sb_inopblog which will
cause ialloc_blks to be zero. If sb_imax_pct is also set, this results
in a division by zero error in the second do_div call. Therefore, force
maxicount to zero if ialloc_blks is zero.
Note that the kernel metadata verifiers will catch the garbage inopblog
value and abort the fs mount long before it tries to set up the inode
geometry; this is needed to avoid a crash in xfs_db while setting up the
xfs_mount structure.
Found by fuzzing sb_inopblog to 122 in xfs/350.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
| -rw-r--r-- | fs/xfs/libxfs/xfs_ialloc.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c index 04377ab75863..588d44613094 100644 --- a/fs/xfs/libxfs/xfs_ialloc.c +++ b/fs/xfs/libxfs/xfs_ialloc.c @@ -2787,8 +2787,13 @@ xfs_ialloc_setup_geometry( igeo->inobt_maxlevels = xfs_btree_compute_maxlevels(igeo->inobt_mnr, inodes); - /* Set the maximum inode count for this filesystem. */ - if (sbp->sb_imax_pct) { + /* + * Set the maximum inode count for this filesystem, being careful not + * to use obviously garbage sb_inopblog/sb_inopblock values. Regular + * users should never get here due to failing sb verification, but + * certain users (xfs_db) need to be usable even with corrupt metadata. + */ + if (sbp->sb_imax_pct && igeo->ialloc_blks) { /* * Make sure the maximum inode count is a multiple * of the units we allocate inodes in. |