From: Miklos Szeredi <[email protected]> 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 <[email protected]> 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 <[email protected]> Cc: Theodore Ts'o <[email protected]> Cc: David Howells <[email protected]> Cc: Al Viro <[email protected]> Cc: <[email protected]> # v4.5 --- fs/ext4/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index feb9ffc6f20d..38847f38b34a 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -380,7 +380,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp) 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, -- 2.1.4
