ubifs: Fix memory leak in do_rename

mainline inclusion
from mainline-v6.4-rc1
commit 3a36d20e
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7JO0G
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3a36d20e012903f45714df2731261fdefac900cb

--------------------------------

If renaming a file in an encrypted directory, function
fscrypt_setup_filename allocates memory for a file name. This name is
never used, and before returning to the caller the memory for it is not
freed.

When running kmemleak on it we see that it is registered as a leak. The
report below is triggered by a simple program 'rename' that renames a
file in an encrypted directory:

  unreferenced object 0xffff888101502840 (size 32):
    comm "rename", pid 9404, jiffies 4302582475 (age 435.735s)
    backtrace:
      __kmem_cache_alloc_node
      __kmalloc
      fscrypt_setup_filename
      do_rename
      ubifs_rename
      vfs_rename
      do_renameat2

To fix this we can remove the call to fscrypt_setup_filename as it's not
needed.

Fixes: 278d9a24 ("ubifs: Rename whiteout atomically")
Reported-by: NZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: NMårten Lindahl <marten.lindahl@axis.com>
Reviewed-by: NZhihao Cheng <chengzhihao1@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: NRichard Weinberger <richard@nod.at>
Signed-off-by: NZhaoLong Wang <wangzhaolong1@huawei.com>
(cherry picked from commit 6bc63230)

fs/ubifs/dir.c

@@ -357,7 +357,6 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
 	umode_t mode = S_IFCHR | WHITEOUT_MODE;
 	struct inode *inode;
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
-	struct fscrypt_name nm;
 
 	/*
 	 * Create an inode('nlink = 1') for whiteout without updating journal,
@@ -368,10 +367,6 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
 	dbg_gen("dent '%pd', mode %#hx in dir ino %lu",
 		dentry, mode, dir->i_ino);
 
-	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
-	if (err)
-		return ERR_PTR(err);
-
 	inode = ubifs_new_inode(c, dir, mode, false);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
@@ -394,7 +389,6 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
 	make_bad_inode(inode);
 	iput(inode);
 out_free:
-	fscrypt_free_filename(&nm);
 	ubifs_err(c, "cannot create whiteout file, error %d", err);
 	return ERR_PTR(err);
 }