Patchwork ext4: use atomic64_t for the per-flexbg free_clusters count

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Submitter Theodore Ts'o
Date March 12, 2013, 3:44 a.m.
Message ID <1363059885-29942-1-git-send-email-tytso@mit.edu>
Download mbox | patch
Permalink /patch/226753/
State Accepted
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Comments

Theodore Ts'o - March 12, 2013, 3:44 a.m.
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

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

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext4/ext4.h    |  6 +++---
 fs/ext4/ialloc.c  |  4 ++--
 fs/ext4/mballoc.c | 12 ++++++------
 fs/ext4/resize.c  |  4 ++--
 fs/ext4/super.c   |  4 ++--
 5 files changed, 15 insertions(+), 15 deletions(-)
Theodore Ts'o - March 12, 2013, 1:45 p.m.
On Mon, Mar 11, 2013 at 11:44:44PM -0400, Theodore Ts'o wrote:
> 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
> 
> Fix this by using an atomic64_t for struct orlav_stats's
> free_clusters.
> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

I should note that this bug was apparently introduced by commit
9f24e4208f7e, so it's been around for a while (since 2.6.30).
Fortunately it's a pretty rare corner case...

						- Ted
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Lukas Czerner - March 12, 2013, 3:09 p.m.
On Mon, 11 Mar 2013, Theodore Ts'o wrote:

> Date: Mon, 11 Mar 2013 23:44:44 -0400
> From: Theodore Ts'o <tytso@mit.edu>
> To: Ext4 Developers List <linux-ext4@vger.kernel.org>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Subject: [PATCH] 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
> 
> Fix this by using an atomic64_t for struct orlav_stats's
> free_clusters.

Looks ok. Thanks!

Reviewed-by: Lukas Czerner <lczerner@redhat.com>

> 
> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
> ---
>  fs/ext4/ext4.h    |  6 +++---
>  fs/ext4/ialloc.c  |  4 ++--
>  fs/ext4/mballoc.c | 12 ++++++------
>  fs/ext4/resize.c  |  4 ++--
>  fs/ext4/super.c   |  4 ++--
>  5 files changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 6ac9b9a..29bb0ac 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -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 */
> diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
> index 32fd2b9..6c5bb8d 100644
> --- a/fs/ext4/ialloc.c
> +++ b/fs/ext4/ialloc.c
> @@ -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;
>  	}
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 8b2ea9f..ee6614b 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);
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index b2c8ee5..c169477 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -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);
>  	}
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9379b7f..d1ee6a8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -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);
>  	}
> 
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Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 6ac9b9a..29bb0ac 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -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 */
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 32fd2b9..6c5bb8d 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -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;
 	}
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 8b2ea9f..ee6614b 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);
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index b2c8ee5..c169477 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -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);
 	}
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9379b7f..d1ee6a8 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -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);
 	}