linux-kernel - [PATCH 4.4 10/86] f2fs crypto: avoid unneeded memory allocation in ->readdir

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Message-Id: <20201109125021.360517842@linuxfoundation.org>
Date:   Mon,  9 Nov 2020 13:54:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chao Yu <yuchao0@...wei.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH 4.4 10/86] f2fs crypto: avoid unneeded memory allocation in ->readdir

From: Chao Yu <yuchao0@...wei.com>

commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b upstream.

When decrypting dirents in ->readdir, fscrypt_fname_disk_to_usr won't
change content of original encrypted dirent, we don't need to allocate
additional buffer for storing mirror of it, so get rid of it.

[This backport fixes a regression in 4.4-stable caused by commit
11a6e8f89521 ("f2fs: check memory boundary by insane namelen"), which
depended on this missing commit.  This bad backport broke f2fs
encryption because it moved the incrementing of 'bit_pos' to earlier in
f2fs_fill_dentries() without accounting for it being used in the
encrypted dir case.  This caused readdir() on encrypted directories to
start failing.  Tested with 'kvm-xfstests -c f2fs -g encrypt'.]

Signed-off-by: Chao Yu <yuchao0@...wei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/f2fs/dir.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -820,15 +820,8 @@ bool f2fs_fill_dentries(struct dir_conte
 			int save_len = fstr->len;
 			int ret;

-			de_name.name = kmalloc(de_name.len, GFP_NOFS);
-			if (!de_name.name)
-				return false;
-
-			memcpy(de_name.name, d->filename[bit_pos], de_name.len);
-
 			ret = f2fs_fname_disk_to_usr(d->inode, &de->hash_code,
 							&de_name, fstr);
-			kfree(de_name.name);
 			if (ret < 0)
 				return true;