[PATCH 4.10 09/81] xfs: check for obviously bad level values in the bmbt root

Greg Kroah-Hartman
2017-04-06T08:45:18Z

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

commit b3bf607d58520ea8c0666aeb4be60dbb724cd3a2 upstream.

We can't handle a bmbt that's taller than BTREE_MAXLEVELS, and there's
no such thing as a zero-level bmbt (for that we have extents format),
so if we see this, send back an error code.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/libxfs/xfs_inode_fork.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -26,6 +26,7 @@
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "xfs_inode_item.h"
+#include "xfs_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_bmap.h"
#include "xfs_error.h"
@@ -429,11 +430,13 @@ xfs_iformat_btree(
/* REFERENCED */
int nrecs;
int size;
+ int level;

ifp = XFS_IFORK_PTR(ip, whichfork);
dfp = (xfs_bmdr_block_t *)XFS_DFORK_PTR(dip, whichfork);
size = XFS_BMAP_BROOT_SPACE(mp, dfp);
nrecs = be16_to_cpu(dfp->bb_numrecs);
+ level = be16_to_cpu(dfp->bb_level);

/*
* blow out if -- fork has less extents than can fit in
@@ -446,7 +449,8 @@ xfs_iformat_btree(
XFS_IFORK_MAXEXT(ip, whichfork) ||
XFS_BMDR_SPACE_CALC(nrecs) >
XFS_DFORK_SIZE(dip, mp, whichfork) ||
- XFS_IFORK_NEXTENTS(ip, whichfork) > ip->i_d.di_nblocks)) {
+ XFS_IFORK_NEXTENTS(ip, whichfork) > ip->i_d.di_nblocks) ||
+ level == 0 || level > XFS_BTREE_MAXLEVELS) {
xfs_warn(mp, "corrupt inode %Lu (btree).",
(unsigned long long) ip->i_ino);
XFS_CORRUPTION_ERROR("xfs_iformat_btree", XFS_ERRLEVEL_LOW,