From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 15 Apr 2017 19:58:56 +0000 (-0400)
Subject: make sure that fchdir() won't accept referral points, etc.
X-Git-Tag: v4.12-rc1~11^2~2
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=159b095628851966b5fbf2637b0c40709911ca88;p=karo-tx-linux.git

make sure that fchdir() won't accept referral points, etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/open.c b/fs/open.c
index 949cef29c3bb..9f4bbd7cc51a 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -459,20 +459,17 @@ out:
 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 {
 	struct fd f = fdget_raw(fd);
-	struct inode *inode;
-	int error = -EBADF;
+	int error;
 
 	error = -EBADF;
 	if (!f.file)
 		goto out;
 
-	inode = file_inode(f.file);
-
 	error = -ENOTDIR;
-	if (!S_ISDIR(inode->i_mode))
+	if (!d_can_lookup(f.file->f_path.dentry))
 		goto out_putf;
 
-	error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
+	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
 	if (!error)
 		set_fs_pwd(current->fs, &f.file->f_path);
 out_putf: