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
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4a01ba3..167ff56 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -335,9 +335,9 @@
*/
struct flex_groups {
- atomic_t free_inodes;
- atomic_t free_clusters;
- atomic_t used_dirs;
+ atomic64_t free_clusters;
+ atomic_t free_inodes;
+ atomic_t used_dirs;
};
#define EXT4_BG_INODE_UNINIT 0x0001 /* Inode table/bitmap not in use */