xfs: fix overflow in xfs_attr3_leaf_verify

[sfrench/cifs-2.6.git] / fs / xfs / libxfs / xfs_attr_leaf.c

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 6fc5425b1474a52694b4860aa79cefc52d3fd826..2652d00842d6ba8c6479f816765c87dfc622d1cb 100644 (file)
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -243,7 +243,7 @@ xfs_attr3_leaf_verify(
        struct xfs_mount                *mp = bp->b_target->bt_mount;
        struct xfs_attr_leafblock       *leaf = bp->b_addr;
        struct xfs_attr_leaf_entry      *entries;
-       uint16_t                        end;
+       uint32_t                        end;    /* must be 32bit - see below */
        int                             i;
 
        xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
@@ -293,6 +293,11 @@ xfs_attr3_leaf_verify(
        /*
         * Quickly check the freemap information.  Attribute data has to be
         * aligned to 4-byte boundaries, and likewise for the free space.
+        *
+        * Note that for 64k block size filesystems, the freemap entries cannot
+        * overflow as they are only be16 fields. However, when checking end
+        * pointer of the freemap, we have to be careful to detect overflows and
+        * so use uint32_t for those checks.
         */
        for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
                if (ichdr.freemap[i].base > mp->m_attr_geo->blksize)
@@ -303,7 +308,9 @@ xfs_attr3_leaf_verify(
                        return __this_address;
                if (ichdr.freemap[i].size & 0x3)
                        return __this_address;
-               end = ichdr.freemap[i].base + ichdr.freemap[i].size;
+
+               /* be care of 16 bit overflows here */
+               end = (uint32_t)ichdr.freemap[i].base + ichdr.freemap[i].size;
                if (end < ichdr.freemap[i].base)
                        return __this_address;
                if (end > mp->m_attr_geo->blksize)