diff options
| -rw-r--r-- | cipher/cipher-gcm.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/cipher/cipher-gcm.c b/cipher/cipher-gcm.c index cb81ea93..5e9dec48 100644 --- a/cipher/cipher-gcm.c +++ b/cipher/cipher-gcm.c @@ -803,13 +803,18 @@ _gcry_cipher_gcm_tag (gcry_cipher_hd_t c, if (!check) { + /* NB: We already checked that OUTBUF is large enough to hold + the result. */ memcpy (outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN); - return GPG_ERR_NO_ERROR; } else { - return buf_eq_const(outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN) ? - GPG_ERR_NO_ERROR : GPG_ERR_CHECKSUM; + /* OUTBUFLEN gives the length of the user supplied tag in OUTBUF + * and thus we need to compare its length first. */ + if (outbuflen != GCRY_GCM_BLOCK_LEN + || !buf_eq_const (outbuf, c->u_mode.gcm.u_tag.tag, + GCRY_GCM_BLOCK_LEN)) + return GPG_ERR_CHECKSUM; } return 0; |