xfs: fix s_maxbytes overflow problems

Fix some integer overflow problems if offset + count happen to be large
enough to cause an integer overflow.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

2 files changed, 3 insertions, 3 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 21e2d70884e1..4fc526a27a94 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -399,7 +399,7 @@ xfs_map_blocks(
                (ip->i_df.if_flags & XFS_IFEXTENTS));
         ASSERT(offset <= mp->m_super->s_maxbytes);
 
-        if ((xfs_ufsize_t)offset + count > mp->m_super->s_maxbytes)
+        if (offset > mp->m_super->s_maxbytes - count)
                 count = mp->m_super->s_maxbytes - offset;
         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
@@ -1312,7 +1312,7 @@ xfs_get_blocks(
         lockmode = xfs_ilock_data_map_shared(ip);
 
         ASSERT(offset <= mp->m_super->s_maxbytes);
-        if ((xfs_ufsize_t)offset + size > mp->m_super->s_maxbytes)
+        if (offset > mp->m_super->s_maxbytes - size)
                 size = mp->m_super->s_maxbytes - offset;
         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 7ab52a8bc0a9..66e1edbfb2b2 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1006,7 +1006,7 @@ xfs_file_iomap_begin(
         }
 
         ASSERT(offset <= mp->m_super->s_maxbytes);
-        if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes)
+        if (offset > mp->m_super->s_maxbytes - length)
                 length = mp->m_super->s_maxbytes - offset;
         offset_fsb = XFS_B_TO_FSBT(mp, offset);
         end_fsb = XFS_B_TO_FSB(mp, offset + length);