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g10/parse-packet.c:mpi_read: Detect EOF and correct boundary conditions.

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* g10/parse-packet.c (mpi_read): Improve documentation.  Correctly
handle an EOF.  On overflow, correctly return the number of bytes read
from the pipeline.

--
Signed-off-by: Neal H. Walfield <neal@g10code.com>.
This commit is contained in:
Neal H. Walfield 2015-08-18 10:33:06 +02:00
parent 49f922286f
commit c271feb536
1 changed files with 21 additions and 8 deletions
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29
g10/parse-packet.c
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@ -2,6 +2,7 @@
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
* 2007, 2009, 2010 Free Software Foundation, Inc.
* Copyright (C) 2014 Werner Koch
* Copyright (C) 2015 g10 Code GmbH
*
* This file is part of GnuPG.
*
@ -109,11 +110,18 @@ read_32 (IOBUF inp)
}
/* Read an external representation of an mpi and return the MPI. The
* external format is a 16 bit unsigned value stored in network byte
* order, giving the number of bits for the following integer. The
* integer is stored with MSB first (left padded with zero bits to align
* on a byte boundary). */
/* Read an external representation of an MPI and return the MPI. The
external format is a 16-bit unsigned value stored in network byte
order giving the number of bits for the following integer. The
integer is stored MSB first and is left padded with zero bits to
align on a byte boundary.
The caller must set *RET_NREAD to the maximum number of bytes to
read from the pipeline INP. This function sets *RET_NREAD to be
the number of bytes actually read from the pipeline.
If SECURE is true, the integer is stored in secure memory
(allocated using gcry_xmalloc_secure). */
static gcry_mpi_t
mpi_read (iobuf_t inp, unsigned int *ret_nread, int secure)
{
@ -150,10 +158,15 @@ mpi_read (iobuf_t inp, unsigned int *ret_nread, int secure)
p[1] = c2;
for (i = 0; i < nbytes; i++)
{
p[i + 2] = iobuf_get (inp) & 0xff;
if (nread == nmax)
goto overflow;
nread++;
goto overflow;
c = iobuf_get (inp);
if (c == -1)
goto leave;
p[i + 2] = c;
nread ++;
}
if (gcry_mpi_scan (&a, GCRYMPI_FMT_PGP, buf, nread, &nread))