[PATCH v3] ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}

[PATCH v3] ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}

[Luís Henriques]

If the filename casefolding fails, we'll be leaking memory from the
fscrypt_name struct, namely from the 'crypto_buf.name' member.

Make sure we free it in the error path on both ext4_fname_setup_filename()
and ext4_fname_prepare_lookup() functions.

Fixes: 1ae98e295fa2 ("ext4: optimize match for casefolded encrypted dirs")
Signed-off-by: Luís Henriques <lhenriques@suse.de>
---
Changes since v2:
- Rephrased commit log to (hopefully!) make it more clear.
- Use ext4_fname_free_filename() instead of fscrypt_free_filename().
  Although not strictly needed, it cleans up the fname struct, removing a
  dangling pointer to freed memory.

Changes since v1:
- Include fix to ext4_fname_prepare_lookup() as well
- Add 'Fixes:' tag

 fs/ext4/crypto.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index e20ac0654b3f..453d4da5de52 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,
 
 #if IS_ENABLED(CONFIG_UNICODE)
 	err = ext4_fname_setup_ci_filename(dir, iname, fname);
+	if (err)
+		ext4_fname_free_filename(fname);
 #endif
 	return err;
 }
@@ -51,6 +53,8 @@ int ext4_fname_prepare_lookup(struct inode *dir, struct dentry *dentry,
 
 #if IS_ENABLED(CONFIG_UNICODE)
 	err = ext4_fname_setup_ci_filename(dir, &dentry->d_name, fname);
+	if (err)
+		ext4_fname_free_filename(fname);
 #endif
 	return err;
 }

Re: [PATCH v3] ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}

[Eric Biggers]

On Thu, Aug 03, 2023 at 10:17:13AM +0100, Luís Henriques wrote:
> If the filename casefolding fails, we'll be leaking memory from the
> fscrypt_name struct, namely from the 'crypto_buf.name' member.
> 
> Make sure we free it in the error path on both ext4_fname_setup_filename()
> and ext4_fname_prepare_lookup() functions.
> 
> Fixes: 1ae98e295fa2 ("ext4: optimize match for casefolded encrypted dirs")
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
> Changes since v2:
> - Rephrased commit log to (hopefully!) make it more clear.
> - Use ext4_fname_free_filename() instead of fscrypt_free_filename().
>   Although not strictly needed, it cleans up the fname struct, removing a
>   dangling pointer to freed memory.
> 
> Changes since v1:
> - Include fix to ext4_fname_prepare_lookup() as well
> - Add 'Fixes:' tag
> 
>  fs/ext4/crypto.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
> index e20ac0654b3f..453d4da5de52 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,
>  
>  #if IS_ENABLED(CONFIG_UNICODE)
>  	err = ext4_fname_setup_ci_filename(dir, iname, fname);
> +	if (err)
> +		ext4_fname_free_filename(fname);
>  #endif
>  	return err;
>  }
> @@ -51,6 +53,8 @@ int ext4_fname_prepare_lookup(struct inode *dir, struct dentry *dentry,
>  
>  #if IS_ENABLED(CONFIG_UNICODE)
>  	err = ext4_fname_setup_ci_filename(dir, &dentry->d_name, fname);
> +	if (err)
> +		ext4_fname_free_filename(fname);
>  #endif
>  	return err;
>  }

Reviewed-by: Eric Biggers <ebiggers@google.com>

- Eric

Re: [PATCH v3] ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}

[Theodore Ts'o]

On Thu, 03 Aug 2023 10:17:13 +0100, Luís Henriques wrote:
> If the filename casefolding fails, we'll be leaking memory from the
> fscrypt_name struct, namely from the 'crypto_buf.name' member.
> 
> Make sure we free it in the error path on both ext4_fname_setup_filename()
> and ext4_fname_prepare_lookup() functions.
> 
> 
> [...]

Applied, thanks!

[1/1] ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}
      commit: 7ca4b085f430f3774c3838b3da569ceccd6a0177

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>