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Groups > linux.kernel > #1636588

[PATCH 4.4 17/20] ext4 crypto: use dget_parent() in ext4_d_revalidate()

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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

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>
---
 fs/ext4/crypto.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -477,16 +477,21 @@ uint32_t ext4_validate_encryption_key_si
  */
 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

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[PATCH 4.4 00/20] 4.4.67-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 10/20] scsi: cxlflash: Improve EEH recovery time Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 19/20] nfsd4: minor NFSv2/v3 write decoding cleanup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 12/20] netlink: Allow direct reclaim for fallback allocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 14/20] IB/ehca: fix maybe-uninitialized warnings Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 13/20] IB/qib: rename BITS_PER_PAGE to RVT_BITS_PER_PAGE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 17/20] ext4 crypto: use dget_parent() in ext4_d_revalidate() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 18/20] ext4/fscrypto: avoid RCU lookup in d_revalidate Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  [PATCH 4.4 03/20] ASoC: intel: Fix PM and non-atomic crash in bytcr drivers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-05 20:40 +0200
  Re: [PATCH 4.4 00/20] 4.4.67-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-05-06 04:00 +0200
    Re: [PATCH 4.4 00/20] 4.4.67-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-05-06 05:50 +0200
  Re: [PATCH 4.4 00/20] 4.4.67-stable review Guenter Roeck <linux@roeck-us.net> - 2017-05-08 00:10 +0200

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