Opencrypto subsystem has memory leakage when gcm algorithm is used. To make sure the bug exist it's enough to monitor memory usage through "vmstat -m | grep crypto" while opening and freeing new sessions for gcm (the auth part of gcm: CRYPTO_AES_256_NIST_GMAC).

Memory is allocated at swcr_newsession function:

929 	                case CRYPTO_AES_256_NIST_GMAC:
930 	                        axf = &auth_hash_nist_gmac_aes_256;
931 	                auth4common:
932 	                        len = cri->cri_klen / 8;
933 	                        if (len != 16 && len != 24 && len != 32) {
934 	                                swcr_freesession_locked(dev, i);
935 	                                rw_runlock(&swcr_sessions_lock);
936 	                                return EINVAL;
937 	                        }
938 	
939 	                        (*swd)->sw_ictx = malloc(axf->ctxsize, M_CRYPTO_DATA,
940 	                            M_NOWAIT);

and not released in swcr_freesession_locked function. I think it's enough to make something like this in swcr_freesession_locked:

1055 	                case CRYPTO_MD5:
1056 	                case CRYPTO_SHA1:
                        case CRYPTO_AES_128_NIST_GMAC:
                        case CRYPTO_AES_192_NIST_GMAC:
                        case CRYPTO_AES_256_NIST_GMAC:

1057 	                        axf = swd->sw_axf;
1058 	
1059 	                        if (swd->sw_ictx)
1060 	                                free(swd->sw_ictx, M_CRYPTO_DATA);
1061 	                        break;