ima: fix reference leak in asymmetric_verify()

Don't leak a reference to the key if its algorithm is unknown.

Fixes: 947d70597236 ("ima: Support EC keys for signature verification")
Cc: <stable@vger.kernel.org> # v5.13+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index 23240d7..895f4b9 100644 (file)
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -109,22 +109,25 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 
        pk = asymmetric_key_public_key(key);
        pks.pkey_algo = pk->pkey_algo;
-       if (!strcmp(pk->pkey_algo, "rsa"))
+       if (!strcmp(pk->pkey_algo, "rsa")) {
                pks.encoding = "pkcs1";
-       else if (!strncmp(pk->pkey_algo, "ecdsa-", 6))
+       } else if (!strncmp(pk->pkey_algo, "ecdsa-", 6)) {
                /* edcsa-nist-p192 etc. */
                pks.encoding = "x962";
-       else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
-                  !strcmp(pk->pkey_algo, "sm2"))
+       } else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
+                  !strcmp(pk->pkey_algo, "sm2")) {
                pks.encoding = "raw";
-       else
-               return -ENOPKG;
+       } else {
+               ret = -ENOPKG;
+               goto out;
+       }
 
        pks.digest = (u8 *)data;
        pks.digest_size = datalen;
        pks.s = hdr->sig;
        pks.s_size = siglen;
        ret = verify_signature(key, &pks);
+out:
        key_put(key);
        pr_debug("%s() = %d\n", __func__, ret);
        return ret;