Commit 60aa4d55 authored by Sahitya Tummala's avatar Sahitya Tummala Committed by Jaegeuk Kim
Browse files

f2fs: fix use-after-free issue when accessing sbi->stat_info 



iput() on sbi->node_inode can update sbi->stat_info
in the below context, if the f2fs_write_checkpoint()
has failed with error.

f2fs_balance_fs_bg+0x1ac/0x1ec
f2fs_write_node_pages+0x4c/0x260
do_writepages+0x80/0xbc
__writeback_single_inode+0xdc/0x4ac
writeback_single_inode+0x9c/0x144
write_inode_now+0xc4/0xec
iput+0x194/0x22c
f2fs_put_super+0x11c/0x1e8
generic_shutdown_super+0x70/0xf4
kill_block_super+0x2c/0x5c
kill_f2fs_super+0x44/0x50
deactivate_locked_super+0x60/0x8c
deactivate_super+0x68/0x74
cleanup_mnt+0x40/0x78

Fix this by moving f2fs_destroy_stats() further below iput() in
both f2fs_put_super() and f2fs_fill_super() paths.

Signed-off-by: default avatarSahitya Tummala <stummala@codeaurora.org>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent bae0ee7a

fs/f2fs/super.c

+15 −12
Original line number Diff line number Diff line
@@ -1058,9 +1058,6 @@ static void f2fs_put_super(struct super_block *sb) 
		f2fs_write_checkpoint(sbi, &cpc);

	}



	/* f2fs_write_checkpoint can update stat informaion */

	f2fs_destroy_stats(sbi);



	/*

	 * normally superblock is clean, so we need to release this.

	 * In addition, EIO will skip do checkpoint, we need this as well.
@@ -1080,6 +1077,12 @@ static void f2fs_put_super(struct super_block *sb) 
	iput(sbi->node_inode);

	iput(sbi->meta_inode);



	/*

	 * iput() can update stat information, if f2fs_write_checkpoint()

	 * above failed with error.

	 */

	f2fs_destroy_stats(sbi);



	/* destroy f2fs internal modules */

	f2fs_destroy_node_manager(sbi);

	f2fs_destroy_segment_manager(sbi);
@@ -3256,30 +3259,30 @@ try_onemore: 


	f2fs_build_gc_manager(sbi);



	err = f2fs_build_stats(sbi);

	if (err)

		goto free_nm;



	/* get an inode for node space */

	sbi->node_inode = f2fs_iget(sb, F2FS_NODE_INO(sbi));

	if (IS_ERR(sbi->node_inode)) {

		f2fs_msg(sb, KERN_ERR, "Failed to read node inode");

		err = PTR_ERR(sbi->node_inode);

		goto free_nm;

		goto free_stats;

	}



	err = f2fs_build_stats(sbi);

	if (err)

		goto free_node_inode;



	/* read root inode and dentry */

	root = f2fs_iget(sb, F2FS_ROOT_INO(sbi));

	if (IS_ERR(root)) {

		f2fs_msg(sb, KERN_ERR, "Failed to read root inode");

		err = PTR_ERR(root);

		goto free_stats;

		goto free_node_inode;

	}

	if (!S_ISDIR(root->i_mode) || !root->i_blocks ||

			!root->i_size || !root->i_nlink) {

		iput(root);

		err = -EINVAL;

		goto free_stats;

		goto free_node_inode;

	}



	sb->s_root = d_make_root(root); /* allocate root dentry */
@@ -3403,12 +3406,12 @@ free_meta: 
free_root_inode:

	dput(sb->s_root);

	sb->s_root = NULL;

free_stats:

	f2fs_destroy_stats(sbi);

free_node_inode:

	f2fs_release_ino_entry(sbi, true);

	truncate_inode_pages_final(NODE_MAPPING(sbi));

	iput(sbi->node_inode);

free_stats:

	f2fs_destroy_stats(sbi);

free_nm:

	f2fs_destroy_node_manager(sbi);

free_sm:

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