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

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Date:   Tue,  7 Jun 2022 15:46:50 +0800
From:   Jianglei Nie <niejianglei2021@....com>
To:     jejb@...ux.ibm.com, jarkko@...nel.org, zohar@...ux.ibm.com,
        dhowells@...hat.com, jmorris@...ei.org, serge@...lyn.com
Cc:     linux-integrity@...r.kernel.org, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Jianglei Nie <niejianglei2021@....com>
Subject: [PATCH] security:trusted_tpm2: Fix memory leak in tpm2_key_encode()

The function allocates a memory chunk for scratch by kmalloc(), but
it is never freed through the function, which leads to a memory leak.
Handle those cases with kfree().

Signed-off-by: Jianglei Nie <niejianglei2021@....com>
---
 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