4.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
commit c0a37d48788475d0a2cf4fbfaa28559a9de612fc upstream.
EXT4 may be used as lower layer of overlayfs and accessing f_path.dentry
can lead to a crash.
Fix by replacing direct access of file->f_path.dentry with the
file_dentry() accessor, which will always return a native object.
Reported-by: Daniel Axtens <dja@xxxxxxxxxx>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Fixes: ff978b09f973 ("ext4 crypto: move context consistency check to ext4_file_open()")
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/file.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -380,7 +380,7 @@ static int ext4_file_open(struct inode *
return -ENOKEY;
}
- dir = dget_parent(filp->f_path.dentry);
+ dir = dget_parent(file_dentry(filp));
if (ext4_encrypted_inode(d_inode(dir)) &&
!ext4_is_child_context_consistent_with_parent(d_inode(dir), inode)) {
ext4_warning(inode->i_sb,
--
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