xfs: check for obviously bad level values in the bmbt root

Source kernel commit: b3bf607d58520ea8c0666aeb4be60dbb724cd3a2

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: Eric Sandeen <sandeen@sandeen.net>

diff --git a/libxfs/xfs_inode_fork.c b/libxfs/xfs_inode_fork.c
index d11740539191a19e1e4325cd4bfa3f9a66a6e052..8df1d337b8e23299ba9ca1a75e13475b10cfe25b 100644 (file)
--- a/libxfs/xfs_inode_fork.c
+++ b/libxfs/xfs_inode_fork.c
@@ -23,6 +23,7 @@
 #include "xfs_mount.h"
 #include "xfs_inode.h"
 #include "xfs_trans.h"
+#include "xfs_btree.h"
 #include "xfs_bmap_btree.h"
 #include "xfs_bmap.h"
 #include "xfs_trace.h"
@@ -426,11 +427,13 @@ 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
@@ -443,7 +446,8 @@ 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,