ext4: fix memory leak in ext4_fname_setup_filename() error path

[PATCH] ext4: fix memory leak in ext4_fname_setup_filename() error path

Posted by Luís Henriques 2 years, 6 months ago

If casefolding the filename fails, we'll be leaking fscrypt_buf name.
Make sure we free it in the error path.

Signed-off-by: Luís Henriques <lhenriques@suse.de>
---
 fs/ext4/crypto.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index e20ac0654b3f..9e4503b051c4 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)
+		fscrypt_free_filename(&name);
 #endif
 	return err;
 }

Re: [PATCH] ext4: fix memory leak in ext4_fname_setup_filename() error path

Posted by Eric Biggers 2 years, 6 months ago

On Tue, Aug 01, 2023 at 03:41:36PM +0100, Luís Henriques wrote:
> If casefolding the filename fails, we'll be leaking fscrypt_buf name.
> Make sure we free it in the error path.
> 
> Signed-off-by: Luís Henriques <lhenriques@suse.de>
> ---
>  fs/ext4/crypto.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
> index e20ac0654b3f..9e4503b051c4 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)
> +		fscrypt_free_filename(&name);
>  #endif
>  	return err;
>  }

Doesn't ext4_fname_prepare_lookup() have the same bug?

Also, please include a Fixes tag.

- Eric

Re: [PATCH] ext4: fix memory leak in ext4_fname_setup_filename() error path

Posted by Luís Henriques 2 years, 6 months ago

Eric Biggers <ebiggers@kernel.org> writes:

> On Tue, Aug 01, 2023 at 03:41:36PM +0100, Luís Henriques wrote:
>> If casefolding the filename fails, we'll be leaking fscrypt_buf name.
>> Make sure we free it in the error path.
>> 
>> Signed-off-by: Luís Henriques <lhenriques@suse.de>
>> ---
>>  fs/ext4/crypto.c | 2 ++
>>  1 file changed, 2 insertions(+)
>> 
>> diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
>> index e20ac0654b3f..9e4503b051c4 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)
>> +		fscrypt_free_filename(&name);
>>  #endif
>>  	return err;
>>  }
>
> Doesn't ext4_fname_prepare_lookup() have the same bug?

Doh! I looked into that function too and then completely forgot about it.
It may also call fscrypt_setup_filename(), so it has to do the free in the
error path as well.  I'll send out v2 to include that fix too.

> Also, please include a Fixes tag.

Ok, makes sense.  Thanks!

Cheers,
-- 
Luís