[PATCH 6.8 07/23] KEYS: trusted: Fix memory leak in tpm2_key_encode()

Greg Kroah-Hartman
2024-05-23T13:22:18Z

From: Jarkko Sakkinen <jarkko@kernel.org>

commit ffcaa2172cc1a85ddb8b783de96d38ca8855e248 upstream.

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

Cc: stable@vger.kernel.org # +v5.13
Fixes: f2219745250f ("security: keys: trusted: use ASN.1 TPM2 key format for the blobs")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/keys/trusted-keys/trusted_tpm2.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

--- 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 truste
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 truste
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 truste
* 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 truste
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 {