linux-kernel - Re: [PATCH] security:trusted_tpm2: Fix memory leak in tpm2_key

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Date:   Wed, 8 Jun 2022 11:00:19 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Jianglei Nie <niejianglei2021@....com>
Cc:     jejb@...ux.ibm.com, zohar@...ux.ibm.com, dhowells@...hat.com,
        jmorris@...ei.org, serge@...lyn.com,
        linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] security:trusted_tpm2: Fix memory leak in
 tpm2_key_encode()

The short summary (as mentioned in review):

"KEYS: trusted: Fix memory leak in tpm2_key_encode()"

Also, you should version your patches, and provide a change log.

See: https://www.kernel.org/doc/html/v5.18/process/submitting-patches.html#the-canonical-patch-format

For git format-patch  you can simply supply "-vX" to get
the-canonical-patch-format version included.

On Wed, Jun 08, 2022 at 10:59:38AM +0800, Jianglei Nie wrote:
> tpm2_key_encode() allocates a memory chunk from scratch with kmalloc(),
> but it is never freed, which leads to a memory leak. Free the memory
> chunk with kfree() in the return path.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@....com>
> ---

Here you can write:

v3:
...
v2:
...

>  security/keys/trusted-keys/trusted_tpm2.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
> index 0165da386289..dc9efd6c8b14 100644
> --- a/security/keys/trusted-keys/trusted_tpm2.c
> +++ b/security/keys/trusted-keys/trusted_tpm2.c
> @@ -57,8 +57,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
>  		unsigned char bool[3], *w = bool;
>  		/* tag 0 is emptyAuth */
>  		w = asn1_encode_boolean(w, w + sizeof(bool), true);
> -		if (WARN(IS_ERR(w), "BUG: Boolean failed to encode"))
> +		if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) {
> +			kfree(scratch);
>  			return PTR_ERR(w);
> +		}
>  		work = asn1_encode_tag(work, end_work, 0, bool, w - bool);
>  	}
>  
> @@ -69,8 +71,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
>  	 * trigger, so if it does there's something nefarious going on
>  	 */
>  	if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE,
> -		 "BUG: scratch buffer is too small"))
> +		 "BUG: scratch buffer is too small")) {
> +		kfree(scratch);
>  		return -EINVAL;
> +	}
>  
>  	work = asn1_encode_integer(work, end_work, options->keyhandle);
>  	work = asn1_encode_octet_string(work, end_work, pub, pub_len);
> @@ -79,8 +83,10 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
>  	work1 = payload->blob;
>  	work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob),
>  				     scratch, work - scratch);
> -	if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed"))
> +	if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) {
> +		kfree(scratch);
>  		return PTR_ERR(work1);
> +	}
>  
>  	return work1 - payload->blob;
>  }
> -- 
> 2.25.1
> 

BR, Jarkko