ext4: use atomic64_t for the per-flexbg free_clusters count

A user who was using a 8TB+ file system and with a very large flexbg
size (> 65536) could cause the atomic_t used in the struct flex_groups
to overflow.  This was detected by PaX security patchset:

http://forums.grsecurity.net/viewtopic.php?f=3&t=3289&p=12551#p12551

This bug was introduced in commit 9f24e4208f7e, so it's been around
since 2.6.30.  :-(

Fix this by using an atomic64_t for struct orlav_stats's
free_clusters.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 8b2ea9f75004..ee6614bdb639 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2804,8 +2804,8 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi,
                                                           ac->ac_b_ex.fe_group);
-                atomic_sub(ac->ac_b_ex.fe_len,
-                           &sbi->s_flex_groups[flex_group].free_clusters);
+                atomic64_sub(ac->ac_b_ex.fe_len,
+                             &sbi->s_flex_groups[flex_group].free_clusters);
         }
 
         err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
@@ -4661,8 +4661,8 @@ do_more:
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
-                atomic_add(count_clusters,
-                           &sbi->s_flex_groups[flex_group].free_clusters);
+                atomic64_add(count_clusters,
+                             &sbi->s_flex_groups[flex_group].free_clusters);
         }
 
         ext4_mb_unload_buddy(&e4b);
@@ -4804,8 +4804,8 @@ int ext4_group_add_blocks(handle_t *handle, struct super_block *sb,
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi, block_group);
-                atomic_add(EXT4_NUM_B2C(sbi, blocks_freed),
-                           &sbi->s_flex_groups[flex_group].free_clusters);
+                atomic64_add(EXT4_NUM_B2C(sbi, blocks_freed),
+                             &sbi->s_flex_groups[flex_group].free_clusters);
         }
 
         ext4_mb_unload_buddy(&e4b);