ext4: use atomic64_t for the per-flexbg free_clusters count
Theodore Ts'o [Tue, 12 Mar 2013 03:39:59 +0000 (23:39 -0400)]
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

fs/ext4/ext4.h
fs/ext4/ialloc.c
fs/ext4/mballoc.c
fs/ext4/resize.c
fs/ext4/super.c

index 4a01ba3..167ff56 100644 (file)
@@ -335,9 +335,9 @@ struct ext4_group_desc
  */
 
 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 */
index 32fd2b9..6c5bb8d 100644 (file)
@@ -324,8 +324,8 @@ error_return:
 }
 
 struct orlov_stats {
+       __u64 free_clusters;
        __u32 free_inodes;
-       __u32 free_clusters;
        __u32 used_dirs;
 };
 
@@ -342,7 +342,7 @@ static void get_orlov_stats(struct super_block *sb, ext4_group_t g,
 
        if (flex_size > 1) {
                stats->free_inodes = atomic_read(&flex_group[g].free_inodes);
-               stats->free_clusters = atomic_read(&flex_group[g].free_clusters);
+               stats->free_clusters = atomic64_read(&flex_group[g].free_clusters);
                stats->used_dirs = atomic_read(&flex_group[g].used_dirs);
                return;
        }
index 8b2ea9f..ee6614b 100644 (file)
@@ -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);
index b2c8ee5..c169477 100644 (file)
@@ -1360,8 +1360,8 @@ static void ext4_update_super(struct super_block *sb,
            sbi->s_log_groups_per_flex) {
                ext4_group_t flex_group;
                flex_group = ext4_flex_group(sbi, group_data[0].group);
-               atomic_add(EXT4_NUM_B2C(sbi, free_blocks),
-                          &sbi->s_flex_groups[flex_group].free_clusters);
+               atomic64_add(EXT4_NUM_B2C(sbi, free_blocks),
+                            &sbi->s_flex_groups[flex_group].free_clusters);
                atomic_add(EXT4_INODES_PER_GROUP(sb) * flex_gd->count,
                           &sbi->s_flex_groups[flex_group].free_inodes);
        }
index 9379b7f..d1ee6a8 100644 (file)
@@ -1923,8 +1923,8 @@ static int ext4_fill_flex_info(struct super_block *sb)
                flex_group = ext4_flex_group(sbi, i);
                atomic_add(ext4_free_inodes_count(sb, gdp),
                           &sbi->s_flex_groups[flex_group].free_inodes);
-               atomic_add(ext4_free_group_clusters(sb, gdp),
-                          &sbi->s_flex_groups[flex_group].free_clusters);
+               atomic64_add(ext4_free_group_clusters(sb, gdp),
+                            &sbi->s_flex_groups[flex_group].free_clusters);
                atomic_add(ext4_used_dirs_count(sb, gdp),
                           &sbi->s_flex_groups[flex_group].used_dirs);
        }