From: Bill O'Donnell <billodo@redhat.com>
Date: Thu, 26 Jul 2018 17:10:34 +0000 (-0700)
Subject: libxfs: add more bounds checking to sb sanity checks
X-Git-Tag: v4.19-rc1~175^2~35
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=8756a5af18191a471e670cc577aea60b652fea4c;p=linux.git

libxfs: add more bounds checking to sb sanity checks

Current sb verifier doesn't check bounds on sb_fdblocks and sb_ifree.
Add sanity checks for these parameters.

Signed-off-by: Bill O'Donnell <billodo@redhat.com>
[darrick: port to refactored sb validation predicates]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index f3835e923893..3d29f4a5242f 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -150,6 +150,18 @@ xfs_validate_sb_write(
 	struct xfs_mount	*mp,
 	struct xfs_sb		*sbp)
 {
+	/*
+	 * Carry out additional sb summary counter sanity checks when we write
+	 * the superblock.  We skip this in the read validator because there
+	 * could be newer superblocks in the log and if the values are garbage
+	 * we'll recalculate them at the end of log mount.
+	 */
+	if (sbp->sb_fdblocks > sbp->sb_dblocks ||
+	    sbp->sb_ifree > sbp->sb_icount) {
+		xfs_warn(mp, "SB summary counter sanity check failed");
+		return -EFSCORRUPTED;
+	}
+
 	if (XFS_SB_VERSION_NUM(sbp) != XFS_SB_VERSION_5)
 		return 0;