diff options
| -rw-r--r-- | networking/tls.c | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/networking/tls.c b/networking/tls.c index 3b6347e..69c81b5 100644 --- a/networking/tls.c +++ b/networking/tls.c @@ -348,7 +348,7 @@ static void get_server_hello_or_die(tls_state_t *tls) static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end) { - unsigned len; + unsigned len, len1; if (end - der < 2) xfunc_die(); @@ -358,24 +358,29 @@ static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end) len = der[1]; /* maybe it's short len */ if (len >= 0x80) { /* no */ - if (len != 0x82) { + if (end - der < (int)(len - 0x7e)) /* need 3 or 4 bytes for 81, 82 */ + xfunc_die(); + + len1 = der[2]; + if (len == 0x81) { + /* it's "ii 81 xx" */ + } else if (len == 0x82) { + /* it's "ii 82 xx yy" */ + len1 = 0x100*len1 + der[3]; + der += 1; /* skip [yy] */ + } else { /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */ - /* 0x81 is "1 byte of len", invalid DER */ /* >0x82 is "3+ bytes of len", should not happen realistically */ xfunc_die(); } - if (end - der < 4) - xfunc_die(); - /* it's "ii 82 xx yy" */ - len = 0x100*der[2] + der[3]; + der += 1; /* skip [xx] */ + len = len1; // if (len < 0x80) // xfunc_die(); /* invalid DER: must use short len if can */ - - der += 2; /* skip [code]+[82]+[2byte_len] */ } - der += 2; /* skip [code]+[1byte_len] */ + der += 2; /* skip [code]+[1byte] */ - if (end - der < len) + if (end - der < (int)len) xfunc_die(); *bodyp = der; |