diff options
Diffstat (limited to 'g10/parse-packet.c')
| -rw-r--r-- | g10/parse-packet.c | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/g10/parse-packet.c b/g10/parse-packet.c index 7c54a1ca8..3f3920dac 100644 --- a/g10/parse-packet.c +++ b/g10/parse-packet.c @@ -188,6 +188,22 @@ mpi_read (iobuf_t inp, unsigned int *ret_nread, int secure) } +/* Return an object for SOS which represents MPI(0). */ +static gcry_mpi_t +sos_zero (void) +{ + /* + * We don't do gcry_mpi_set_opaque (NULL, NULL, 0), becase it may + * cause undefined behavior. We use a kind of cork stopper to avoid + * undefined behavior. + */ + byte *buf = gcry_xcalloc (1, 1); + gcry_mpi_t a = gcry_mpi_set_opaque (NULL, buf, 1); + gcry_mpi_set_flag (a, GCRYMPI_FLAG_USER2); + return a; +} + + /* Read an external representation of an SOS and return the opaque MPI with GCRYMPI_FLAG_USER2. The external format is a 16-bit unsigned value stored in network byte order giving information for the @@ -222,7 +238,12 @@ sos_read (iobuf_t inp, unsigned int *ret_nread, int secure) goto leave; ++nread; nbits |= c; - if (nbits > MAX_EXTERN_MPI_BITS) + if (nbits == 0) + { + *ret_nread = nread; + return sos_zero (); + } + else if (nbits > MAX_EXTERN_MPI_BITS) { log_error ("mpi too large (%u bits)\n", nbits); goto leave; @@ -231,8 +252,6 @@ sos_read (iobuf_t inp, unsigned int *ret_nread, int secure) nbytes = (nbits + 7) / 8; if (nbytes) buf = secure ? gcry_xmalloc_secure (nbytes) : gcry_xmalloc (nbytes); - else - buf = NULL; p = buf; for (i = 0; i < nbytes; i++) { @@ -2378,9 +2397,12 @@ parse_signature (IOBUF inp, int pkttype, unsigned long pktlen, } if (!sig->data[i]) rc = GPG_ERR_INV_PACKET; - if (!pktlen && sig->pubkey_algo == PUBKEY_ALGO_EDDSA) - /* Allow the R part only. */ - break; + if (i == 0 && !pktlen && sig->pubkey_algo == PUBKEY_ALGO_EDDSA) + { + /* Accept the case: R part only, missing S. */ + sig->data[1] = sos_zero (); + break; + } } } |