Commit d16c842e authored Mar 26, 2016 by Theodore Ts'o Committed by Eric Biggers May 25, 2017

UPSTREAM: ext4 crypto: use dget_parent() in ext4_d_revalidate()



commit 3d43bcfef5f0548845a425365011c499875491b0 upstream.

This avoids potential problems caused by a race where the inode gets
renamed out from its parent directory and the parent directory is
deleted while ext4_d_revalidate() is running.

Fixes: 28b4c263961c
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 41948f88a521b95e8abc793602015a6d45f52a06)
Change-Id: Icea8f440a708274ecfa12d0c2a392b6aa3cc22c4
Signed-off-by: Eric Biggers <ebiggers@google.com>

parent fa9d8ddc

fs/ext4/crypto.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -478,16 +478,21 @@ uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
		*/
		static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
		{
		struct inode *dir = d_inode(dentry->d_parent);
		struct ext4_crypt_info *ci = EXT4_I(dir)->i_crypt_info;
		struct dentry *dir;
		struct ext4_crypt_info *ci;
		int dir_has_key, cached_with_key;

		if (!ext4_encrypted_inode(dir))
		dir = dget_parent(dentry);
		if (!ext4_encrypted_inode(d_inode(dir))) {
		dput(dir);
		return 0;
		}
		ci = EXT4_I(d_inode(dir))->i_crypt_info;

		/* this should eventually be an flag in d_flags */
		cached_with_key = dentry->d_fsdata != NULL;
		dir_has_key = (ci != NULL);
		dput(dir);

		/*
		* If the dentry was cached without the key, and it is a