[PATCH v2] KEYS: trusted: Fix memory leak in tpm2_key_encode()

Jianglei Nie
2022-06-08T14:36:33Z

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@163.com>
---
security/keys/trusted-keys/trusted_tpm2.c | 24 +++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 0165da386289..6fd426212386 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -32,6 +32,7 @@ static int tpm2_key_encode(struct trusted_key_payload *payload,
struct trusted_key_options *options,
u8 *src, u32 len)
{
+ int err;
const int SCRATCH_SIZE = PAGE_SIZE;
u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL);
u8 *work = scratch, *work1;
@@ -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")) {
+ err = PTR_ERR(w);
+ goto out;
+ }
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")) {
+ err = -EINVAL;
+ goto out;
+ }

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")) {
+ err = -EINVAL;
+ goto out;
+ }
+ kfree(scratch);

return work1 - payload->blob;
+
+out:
+ kfree(scratch);
+ return err;
}

struct tpm2_key_context {
--
2.25.1