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Commit 63edbce1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull ubifs fixes from Al Viro:
 "A couple of ubifs readdir/lseek race fixes.  Stable fodder, really
  nasty..."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  UBIFS: fix a horrid bug
  UBIFS: prepare to fix a horrid bug
parents a61aef7f 605c912b

fs/ubifs/dir.c

+39 −15
Original line number Diff line number Diff line
@@ -349,31 +349,50 @@ static unsigned int vfs_dent_type(uint8_t type) 
static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir)

{

	int err, over = 0;

	loff_t pos = file->f_pos;

	struct qstr nm;

	union ubifs_key key;

	struct ubifs_dent_node *dent;

	struct inode *dir = file_inode(file);

	struct ubifs_info *c = dir->i_sb->s_fs_info;



	dbg_gen("dir ino %lu, f_pos %#llx", dir->i_ino, file->f_pos);

	dbg_gen("dir ino %lu, f_pos %#llx", dir->i_ino, pos);



	if (file->f_pos > UBIFS_S_KEY_HASH_MASK || file->f_pos == 2)

	if (pos > UBIFS_S_KEY_HASH_MASK || pos == 2)

		/*

		 * The directory was seek'ed to a senseless position or there

		 * are no more entries.

		 */

		return 0;



	if (file->f_version == 0) {

		/*

		 * The file was seek'ed, which means that @file->private_data

		 * is now invalid. This may also be just the first

		 * 'ubifs_readdir()' invocation, in which case

		 * @file->private_data is NULL, and the below code is

		 * basically a no-op.

		 */

		kfree(file->private_data);

		file->private_data = NULL;

	}



	/*

	 * 'generic_file_llseek()' unconditionally sets @file->f_version to

	 * zero, and we use this for detecting whether the file was seek'ed.

	 */

	file->f_version = 1;



	/* File positions 0 and 1 correspond to "." and ".." */

	if (file->f_pos == 0) {

	if (pos == 0) {

		ubifs_assert(!file->private_data);

		over = filldir(dirent, ".", 1, 0, dir->i_ino, DT_DIR);

		if (over)

			return 0;

		file->f_pos = 1;

		file->f_pos = pos = 1;

	}



	if (file->f_pos == 1) {

	if (pos == 1) {

		ubifs_assert(!file->private_data);

		over = filldir(dirent, "..", 2, 1,

			       parent_ino(file->f_path.dentry), DT_DIR);
@@ -389,7 +408,7 @@ static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir) 
			goto out;

		}



		file->f_pos = key_hash_flash(c, &dent->key);

		file->f_pos = pos = key_hash_flash(c, &dent->key);

		file->private_data = dent;

	}
@@ -397,17 +416,16 @@ static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir) 
	if (!dent) {

		/*

		 * The directory was seek'ed to and is now readdir'ed.

		 * Find the entry corresponding to @file->f_pos or the

		 * closest one.

		 * Find the entry corresponding to @pos or the closest one.

		 */

		dent_key_init_hash(c, &key, dir->i_ino, file->f_pos);

		dent_key_init_hash(c, &key, dir->i_ino, pos);

		nm.name = NULL;

		dent = ubifs_tnc_next_ent(c, &key, &nm);

		if (IS_ERR(dent)) {

			err = PTR_ERR(dent);

			goto out;

		}

		file->f_pos = key_hash_flash(c, &dent->key);

		file->f_pos = pos = key_hash_flash(c, &dent->key);

		file->private_data = dent;

	}
@@ -419,7 +437,7 @@ static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir) 
			     ubifs_inode(dir)->creat_sqnum);



		nm.len = le16_to_cpu(dent->nlen);

		over = filldir(dirent, dent->name, nm.len, file->f_pos,

		over = filldir(dirent, dent->name, nm.len, pos,

			       le64_to_cpu(dent->inum),

			       vfs_dent_type(dent->type));

		if (over)
@@ -435,9 +453,17 @@ static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir) 
		}



		kfree(file->private_data);

		file->f_pos = key_hash_flash(c, &dent->key);

		file->f_pos = pos = key_hash_flash(c, &dent->key);

		file->private_data = dent;

		cond_resched();



		if (file->f_version == 0)

			/*

			 * The file was seek'ed meanwhile, lets return and start

			 * reading direntries from the new position on the next

			 * invocation.

			 */

			return 0;

	}



out:
@@ -448,15 +474,13 @@ static int ubifs_readdir(struct file *file, void *dirent, filldir_t filldir) 


	kfree(file->private_data);

	file->private_data = NULL;

	/* 2 is a special value indicating that there are no more direntries */

	file->f_pos = 2;

	return 0;

}



/* If a directory is seeked, we have to free saved readdir() state */

static loff_t ubifs_dir_llseek(struct file *file, loff_t offset, int whence)

{

	kfree(file->private_data);

	file->private_data = NULL;

	return generic_file_llseek(file, offset, whence);

}