KEYS: trusted: Fix memory leak in tpm2_key_encode()

'scratch' is never freed. Fix this by calling kfree() in the success, and
in the error case.

Cc: [email protected] # +v5.13
Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs")
Signed-off-by: Jarkko Sakkinen <[email protected]>

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index dfeec06301cea3fe3978b84f619435ed837f7d9e..c6882f5d094f91b7bfab0c03b14c5b5398f00dc6 100644 (file)
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -38,6 +38,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
        u8 *end_work = scratch + SCRATCH_SIZE;
        u8 *priv, *pub;
        u16 priv_len, pub_len;
+       int ret;
 
        priv_len = get_unaligned_be16(src) + 2;
        priv = src;
@@ -57,8 +58,10 @@ 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"))
-                       return PTR_ERR(w);
+               if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) {
+                       ret = PTR_ERR(w);
+                       goto err;
+               }
                work = asn1_encode_tag(work, end_work, 0, bool, w - bool);
        }
 
@@ -69,8 +72,10 @@ 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"))
-               return -EINVAL;
+                "BUG: scratch buffer is too small")) {
+               ret = -EINVAL;
+               goto err;
+       }
 
        work = asn1_encode_integer(work, end_work, options->keyhandle);
        work = asn1_encode_octet_string(work, end_work, pub, pub_len);
@@ -79,10 +84,17 @@ 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"))
-               return PTR_ERR(work1);
+       if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) {
+               ret = PTR_ERR(work1);
+               goto err;
+       }
 
+       kfree(scratch);
        return work1 - payload->blob;
+
+err:
+       kfree(scratch);
+       return ret;
 }
 
 struct tpm2_key_context {