From 723e2b11da1a7698db17e73835c158bb4f6101f0 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Fri, 4 Dec 2020 13:28:35 -0800
Subject: xfs: refactor file range validation

Refactor all the open-coded validation of file block ranges into a
single helper, and teach the bmap scrubber to check the ranges.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c  |  2 +-
 fs/xfs/libxfs/xfs_types.c | 25 +++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_types.h |  3 +++
 fs/xfs/scrub/bmap.c       |  4 ++++
 fs/xfs/xfs_bmap_item.c    |  2 +-
 fs/xfs/xfs_rmap_item.c    |  2 +-
 6 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 7bcf498ef6b2..dcf56bcafb8f 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -6227,7 +6227,7 @@ xfs_bmap_validate_extent(
 {
 	struct xfs_mount	*mp = ip->i_mount;
 
-	if (irec->br_startoff + irec->br_blockcount <= irec->br_startoff)
+	if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
 		return __this_address;
 
 	if (XFS_IS_REALTIME_INODE(ip) && whichfork == XFS_DATA_FORK) {
diff --git a/fs/xfs/libxfs/xfs_types.c b/fs/xfs/libxfs/xfs_types.c
index 7b310eb296b7..b254fbeaaa50 100644
--- a/fs/xfs/libxfs/xfs_types.c
+++ b/fs/xfs/libxfs/xfs_types.c
@@ -258,3 +258,28 @@ xfs_verify_dablk(
 
 	return dabno <= max_dablk;
 }
+
+/* Check that a file block offset does not exceed the maximum. */
+bool
+xfs_verify_fileoff(
+	struct xfs_mount	*mp,
+	xfs_fileoff_t		off)
+{
+	return off <= XFS_MAX_FILEOFF;
+}
+
+/* Check that a range of file block offsets do not exceed the maximum. */
+bool
+xfs_verify_fileext(
+	struct xfs_mount	*mp,
+	xfs_fileoff_t		off,
+	xfs_fileoff_t		len)
+{
+	if (off + len <= off)
+		return false;
+
+	if (!xfs_verify_fileoff(mp, off))
+		return false;
+
+	return xfs_verify_fileoff(mp, off + len - 1);
+}
diff --git a/fs/xfs/libxfs/xfs_types.h b/fs/xfs/libxfs/xfs_types.h
index 18e83ce46568..064bd6e8c922 100644
--- a/fs/xfs/libxfs/xfs_types.h
+++ b/fs/xfs/libxfs/xfs_types.h
@@ -203,5 +203,8 @@ bool xfs_verify_icount(struct xfs_mount *mp, unsigned long long icount);
 bool xfs_verify_dablk(struct xfs_mount *mp, xfs_fileoff_t off);
 void xfs_icount_range(struct xfs_mount *mp, unsigned long long *min,
 		unsigned long long *max);
+bool xfs_verify_fileoff(struct xfs_mount *mp, xfs_fileoff_t off);
+bool xfs_verify_fileext(struct xfs_mount *mp, xfs_fileoff_t off,
+		xfs_fileoff_t len);
 
 #endif	/* __XFS_TYPES_H__ */
diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index cce8ac7d3973..bce4421acdb9 100644
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -329,6 +329,10 @@ xchk_bmap_iextent(
 		xchk_fblock_set_corrupt(info->sc, info->whichfork,
 				irec->br_startoff);
 
+	if (!xfs_verify_fileext(mp, irec->br_startoff, irec->br_blockcount))
+		xchk_fblock_set_corrupt(info->sc, info->whichfork,
+				irec->br_startoff);
+
 	xchk_bmap_dirattr_extent(ip, info, irec);
 
 	/* There should never be a "hole" extent in either extent list. */
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index 5c9706760e68..9a2e54b7ccb9 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -449,7 +449,7 @@ xfs_bui_validate(
 	if (!xfs_verify_ino(mp, bmap->me_owner))
 		return false;
 
-	if (bmap->me_startoff + bmap->me_len <= bmap->me_startoff)
+	if (!xfs_verify_fileext(mp, bmap->me_startoff, bmap->me_len))
 		return false;
 
 	return xfs_verify_fsbext(mp, bmap->me_startblock, bmap->me_len);
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 4fa875237422..49cebd68b672 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -490,7 +490,7 @@ xfs_rui_validate_map(
 	    !xfs_verify_ino(mp, rmap->me_owner))
 		return false;
 
-	if (rmap->me_startoff + rmap->me_len <= rmap->me_startoff)
+	if (!xfs_verify_fileext(mp, rmap->me_startoff, rmap->me_len))
 		return false;
 
 	return xfs_verify_fsbext(mp, rmap->me_startblock, rmap->me_len);
-- 
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