Commit 90ba983f authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

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 9f24e420, 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: default avatar"Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: default avatarLukas Czerner <lczerner@redhat.com>
Cc: stable@vger.kernel.org
parent ad56edad

fs/ext4/ext4.h

+3 −3
Original line number Diff line number Diff line
@@ -335,8 +335,8 @@ struct ext4_group_desc 
 */



struct flex_groups {

	atomic64_t	free_clusters;

	atomic_t	free_inodes;

	atomic_t free_clusters;

	atomic_t	used_dirs;

};

fs/ext4/ialloc.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

	}

fs/ext4/mballoc.c

+6 −6
Original line number Diff line number Diff line
@@ -2804,7 +2804,7 @@ 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,

		atomic64_sub(ac->ac_b_ex.fe_len,

			     &sbi->s_flex_groups[flex_group].free_clusters);

	}
@@ -4661,7 +4661,7 @@ do_more: 


	if (sbi->s_log_groups_per_flex) {

		ext4_group_t flex_group = ext4_flex_group(sbi, block_group);

		atomic_add(count_clusters,

		atomic64_add(count_clusters,

			     &sbi->s_flex_groups[flex_group].free_clusters);

	}
@@ -4804,7 +4804,7 @@ 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),

		atomic64_add(EXT4_NUM_B2C(sbi, blocks_freed),

			     &sbi->s_flex_groups[flex_group].free_clusters);

	}

fs/ext4/resize.c

+2 −2
Original line number Diff line number Diff line
@@ -1360,7 +1360,7 @@ 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),

		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);

fs/ext4/super.c

+2 −2
Original line number Diff line number Diff line
@@ -1923,7 +1923,7 @@ 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),

		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);

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