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Message-ID: <20230803041918.GA1218@sol.localdomain>
Date: Wed, 2 Aug 2023 21:19:18 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: Luís Henriques <lhenriques@...e.de>
Cc: Theodore Ts'o <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
Daniel Rosenberg <drosen@...gle.com>,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ext4: fix memory leaks in
ext4_fname_{setup_filename,prepare_lookup}
On Wed, Aug 02, 2023 at 10:49:31AM +0100, Luís Henriques wrote:
> If casefolding the filename fails, we'll be leaking fscrypt_buf name.
fscrypt_buf => fscrypt_name
> diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
> index e20ac0654b3f..3c05c7f3415b 100644
> --- a/fs/ext4/crypto.c
> +++ b/fs/ext4/crypto.c
> @@ -33,6 +33,8 @@ int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname,
> struct fscrypt_name name;
> int err;
>
> err = fscrypt_setup_filename(dir, iname, lookup, &name);
> if (err)
> return err;
>
> ext4_fname_from_fscrypt_name(fname, &name);
>
> #if IS_ENABLED(CONFIG_UNICODE)
> err = ext4_fname_setup_ci_filename(dir, iname, fname);
> + if (err)
> + fscrypt_free_filename(&name);
> #endif
> return err;
> }
> @@ -51,6 +53,8 @@ int ext4_fname_prepare_lookup(struct inode *dir, struct dentry *dentry,
> struct fscrypt_name name;
> int err;
>
> err = fscrypt_prepare_lookup(dir, dentry, &name);
> if (err)
> return err;
>
> ext4_fname_from_fscrypt_name(fname, &name);
>
> #if IS_ENABLED(CONFIG_UNICODE)
> err = ext4_fname_setup_ci_filename(dir, &dentry->d_name, fname);
> + if (err)
> + fscrypt_free_filename(&name);
> #endif
> return err;
> }
This works, but it's a bit weird that the freeing happens on the original struct
fscrypt_name after it has already been "moved" to the struct ext4_filename by
ext4_fname_from_fscrypt_name(). That leaves a dangling pointer in the struct
ext4_filename. Maybe you should call ext4_fname_free_filename() instead, even
though it would do some unnecessary work?
- Eric
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