Commit 089e77e1 authored by Elena Reshetova's avatar Elena Reshetova Committed by David Sterba
Browse files

btrfs: convert btrfs_delayed_item.refs from atomic_t to refcount_t 



refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 6de5f18e

fs/btrfs/delayed-inode.c

+9 −9
Original line number Diff line number Diff line
@@ -308,7 +308,7 @@ static struct btrfs_delayed_item *btrfs_alloc_delayed_item(u32 data_len) 
		item->ins_or_del = 0;

		item->bytes_reserved = 0;

		item->delayed_node = NULL;

		atomic_set(&item->refs, 1);

		refcount_set(&item->refs, 1);

	}

	return item;

}
@@ -483,7 +483,7 @@ static void btrfs_release_delayed_item(struct btrfs_delayed_item *item) 
{

	if (item) {

		__btrfs_remove_delayed_item(item);

		if (atomic_dec_and_test(&item->refs))

		if (refcount_dec_and_test(&item->refs))

			kfree(item);

	}

}
@@ -1600,14 +1600,14 @@ bool btrfs_readdir_get_delayed_items(struct inode *inode, 
	mutex_lock(&delayed_node->mutex);

	item = __btrfs_first_delayed_insertion_item(delayed_node);

	while (item) {

		atomic_inc(&item->refs);

		refcount_inc(&item->refs);

		list_add_tail(&item->readdir_list, ins_list);

		item = __btrfs_next_delayed_item(item);

	}



	item = __btrfs_first_delayed_deletion_item(delayed_node);

	while (item) {

		atomic_inc(&item->refs);

		refcount_inc(&item->refs);

		list_add_tail(&item->readdir_list, del_list);

		item = __btrfs_next_delayed_item(item);

	}
@@ -1634,13 +1634,13 @@ void btrfs_readdir_put_delayed_items(struct inode *inode, 


	list_for_each_entry_safe(curr, next, ins_list, readdir_list) {

		list_del(&curr->readdir_list);

		if (atomic_dec_and_test(&curr->refs))

		if (refcount_dec_and_test(&curr->refs))

			kfree(curr);

	}



	list_for_each_entry_safe(curr, next, del_list, readdir_list) {

		list_del(&curr->readdir_list);

		if (atomic_dec_and_test(&curr->refs))

		if (refcount_dec_and_test(&curr->refs))

			kfree(curr);

	}
@@ -1667,7 +1667,7 @@ int btrfs_should_delete_dir_index(struct list_head *del_list, 
		list_del(&curr->readdir_list);

		ret = (curr->key.offset == index);



		if (atomic_dec_and_test(&curr->refs))

		if (refcount_dec_and_test(&curr->refs))

			kfree(curr);



		if (ret)
@@ -1705,7 +1705,7 @@ int btrfs_readdir_delayed_dir_index(struct dir_context *ctx, 
		list_del(&curr->readdir_list);



		if (curr->key.offset < ctx->pos) {

			if (atomic_dec_and_test(&curr->refs))

			if (refcount_dec_and_test(&curr->refs))

				kfree(curr);

			continue;

		}
@@ -1722,7 +1722,7 @@ int btrfs_readdir_delayed_dir_index(struct dir_context *ctx, 
		over = !dir_emit(ctx, name, name_len,

			       location.objectid, d_type);



		if (atomic_dec_and_test(&curr->refs))

		if (refcount_dec_and_test(&curr->refs))

			kfree(curr);



		if (over)

fs/btrfs/delayed-inode.h

+1 −1
Original line number Diff line number Diff line
@@ -80,7 +80,7 @@ struct btrfs_delayed_item { 
	struct list_head readdir_list;	/* used for readdir items */

	u64 bytes_reserved;

	struct btrfs_delayed_node *delayed_node;

	atomic_t refs;

	refcount_t refs;

	int ins_or_del;

	u32 data_len;

	char data[0];

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