[PATCH 4.10 08/81] xfs: filter out obviously bad btree pointers

Greg Kroah-Hartman
2017-04-06T08:45:35Z

From: Darrick J. Wong <darrick.wong@oracle.com>

commit d5a91baeb6033c3392121e4d5c011cdc08dfa9f7 upstream.

Don't let anybody load an obviously bad btree pointer. Since the values
come from disk, we must return an error, not just ASSERT.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/libxfs/xfs_bmap.c | 5 +----
fs/xfs/libxfs/xfs_btree.c | 3 ++-
fs/xfs/libxfs/xfs_btree.h | 2 +-
3 files changed, 4 insertions(+), 6 deletions(-)

--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1278,7 +1278,6 @@ xfs_bmap_read_extents(
/* REFERENCED */
xfs_extnum_t room; /* number of entries there's room for */

- bno = NULLFSBLOCK;
mp = ip->i_mount;
ifp = XFS_IFORK_PTR(ip, whichfork);
exntf = (whichfork != XFS_DATA_FORK) ? XFS_EXTFMT_NOSTATE :
@@ -1291,9 +1290,7 @@ xfs_bmap_read_extents(
ASSERT(level > 0);
pp = XFS_BMAP_BROOT_PTR_ADDR(mp, block, 1, ifp->if_broot_bytes);
bno = be64_to_cpu(*pp);
- ASSERT(bno != NULLFSBLOCK);
- ASSERT(XFS_FSB_TO_AGNO(mp, bno) < mp->m_sb.sb_agcount);
- ASSERT(XFS_FSB_TO_AGBNO(mp, bno) < mp->m_sb.sb_agblocks);
+
/*
* Go down the tree until leaf level is reached, following the first
* pointer (leftmost) at each level.
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -810,7 +810,8 @@ xfs_btree_read_bufl(
xfs_daddr_t d; /* real disk block address */
int error;

- ASSERT(fsbno != NULLFSBLOCK);
+ if (!XFS_FSB_SANITY_CHECK(mp, fsbno))
+ return -EFSCORRUPTED;
d = XFS_FSB_TO_DADDR(mp, fsbno);
error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
mp->m_bsize, lock, &bp, ops);
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -456,7 +456,7 @@ static inline int xfs_btree_get_level(st
#define XFS_FILBLKS_MAX(a,b) max_t(xfs_filblks_t, (a), (b))

#define XFS_FSB_SANITY_CHECK(mp,fsb) \
- (XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
+ (fsb && XFS_FSB_TO_AGNO(mp, fsb) < mp->m_sb.sb_agcount && \
XFS_FSB_TO_AGBNO(mp, fsb) < mp->m_sb.sb_agblocks)

/*