[f2fs-dev] [PATCH 4.4] f2fs crypto: avoid unneeded memory allocation in ->readdir

[f2fs-dev] [PATCH 4.4] f2fs crypto: avoid unneeded memory allocation in ->readdir

[Eric Biggers]

From: Chao Yu <yuchao0@huawei.com>

commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b upstream.
[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'.]

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.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/f2fs/dir.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index e2ff0eb16f89c..c1130914d6ed7 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -820,15 +820,8 @@ bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
 			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;
 
-- 
2.29.1



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Re: [f2fs-dev] [PATCH 4.4] f2fs crypto: avoid unneeded memory allocation in ->readdir

[Greg KH]

On Sat, Oct 31, 2020 at 12:58:09PM -0700, Eric Biggers wrote:
> From: Chao Yu <yuchao0@huawei.com>
> 
> commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b upstream.
> [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'.]
> 
> 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.
> 
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  fs/f2fs/dir.c | 7 -------
>  1 file changed, 7 deletions(-)

Now queued up, thanks.

greg k-h


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