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ext4: fix use-after-iput when fscrypt contexts are inconsistent 

In the case where the child's encryption context was inconsistent with
its parent directory, we were using inode->i_sb and inode->i_ino after
the inode had already been iput().  Fix this by doing the iput() in the
correct places.

Note: only ext4 had this bug, not f2fs and ubifs.

Fixes: d9cdc90331 ("ext4 crypto: enforce context consistency")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Eric Biggers 2017-02-01 21:07:11 -05:00 committed by Theodore Ts'o
parent dbfcef6b0f
commit dd01b690f8
1 changed files with 4 additions and 2 deletions
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6
fs/ext4/namei.c
View File

@ -1618,13 +1618,15 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
!fscrypt_has_permitted_context(dir, inode)) {
int nokey = ext4_encrypted_inode(inode) &&
!fscrypt_has_encryption_key(inode);
iput(inode);
if (nokey)
if (nokey) {
iput(inode);
return ERR_PTR(-ENOKEY);
}
ext4_warning(inode->i_sb,
"Inconsistent encryption contexts: %lu/%lu",
(unsigned long) dir->i_ino,
(unsigned long) inode->i_ino);
iput(inode);
return ERR_PTR(-EPERM);
}
}