From 7222d93072f178e5e5c40a6b1fef8946f35bb4ee Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Sat, 26 Mar 2016 16:14:41 -0400 Subject: [PATCH] ext4: use dget_parent() in ext4_file_open() commit 9dd78d8c9a7bd4bc341f5864db32d4331b8eae4c upstream. In f_op->open() lock on parent is not held, so there's no guarantee that parent dentry won't go away at any time. Even after this patch there's no guarantee that 'dir' will stay the parent of 'inode', but at least it won't be freed while being used. Fixes: ff978b09f973 ("ext4 crypto: move context consistency check to ext4_file_open()") Signed-off-by: Miklos Szeredi Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/file.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 4cd318f31cbef..feb9ffc6f20d4 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -335,7 +335,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp) struct super_block *sb = inode->i_sb; struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); struct vfsmount *mnt = filp->f_path.mnt; - struct inode *dir = filp->f_path.dentry->d_parent->d_inode; + struct dentry *dir; struct path path; char buf[64], *cp; int ret; @@ -379,14 +379,18 @@ static int ext4_file_open(struct inode * inode, struct file * filp) if (ext4_encryption_info(inode) == NULL) return -ENOKEY; } - if (ext4_encrypted_inode(dir) && - !ext4_is_child_context_consistent_with_parent(dir, inode)) { + + dir = dget_parent(filp->f_path.dentry); + if (ext4_encrypted_inode(d_inode(dir)) && + !ext4_is_child_context_consistent_with_parent(d_inode(dir), inode)) { ext4_warning(inode->i_sb, "Inconsistent encryption contexts: %lu/%lu\n", - (unsigned long) dir->i_ino, + (unsigned long) d_inode(dir)->i_ino, (unsigned long) inode->i_ino); + dput(dir); return -EPERM; } + dput(dir); /* * Set up the jbd2_inode if we are opening the inode for * writing and the journal is present -- 2.47.2