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ecryptfs: initialize private persistent file before dereferencing pointer

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Ecryptfs_open dereferences a pointer to the private lower file (the one
stored in the ecryptfs inode), without checking if the pointer is NULL.
Right afterward, it initializes that pointer if it is NULL.  Swap order of
statements to first initialize.  Bug discovered by Duckjin Kang.

Signed-off-by: Duckjin Kang <fromdj2k@gmail.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Cc: Dustin Kirkland <kirkland@canonical.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
This commit is contained in:
Erez Zadok 2009-12-03 13:35:27 -05:00 committed by Tyler Hicks
parent 38e3eaeedc
commit e27759d7a3
1 changed files with 7 additions and 7 deletions
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14
fs/ecryptfs/file.c
View file

@ -191,13 +191,6 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
| ECRYPTFS_ENCRYPTED);
}
mutex_unlock(&crypt_stat->cs_mutex);
if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
&& !(file->f_flags & O_RDONLY)) {
rc = -EPERM;
printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
"file must hence be opened RO\n", __func__);
goto out;
}
if (!ecryptfs_inode_to_private(inode)->lower_file) {
rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
if (rc) {
@ -208,6 +201,13 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
goto out;
}
}
if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
&& !(file->f_flags & O_RDONLY)) {
rc = -EPERM;
printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
"file must hence be opened RO\n", __func__);
goto out;
}
ecryptfs_set_file_lower(
file, ecryptfs_inode_to_private(inode)->lower_file);
if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {