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Commit 9cbe21d8 authored by Andrzej Zaborowski's avatar Andrzej Zaborowski Committed by Herbert Xu
Browse files

lib/mpi: only require buffers as big as needed for the integer 



Since mpi_write_to_sgl and mpi_read_buffer explicitly left-align the
integers being written it makes no sense to require a buffer big enough for
the number + the leading zero bytes which are not written.  The error
returned also doesn't convey any information.  So instead require only the
size needed and return -EOVERFLOW to signal when buffer too short.

Signed-off-by: default avatarAndrew Zaborowski <andrew.zaborowski@intel.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 7aff7d0a

lib/mpi/mpicoder.c

+17 −4
Original line number Diff line number Diff line
@@ -135,7 +135,9 @@ EXPORT_SYMBOL_GPL(mpi_read_from_buffer); 
 * @buf:	bufer to which the output will be written to. Needs to be at

 *		leaset mpi_get_size(a) long.

 * @buf_len:	size of the buf.

 * @nbytes:	receives the actual length of the data written.

 * @nbytes:	receives the actual length of the data written on success and

 *		the data to-be-written on -EOVERFLOW in case buf_len was too

 *		small.

 * @sign:	if not NULL, it will be set to the sign of a.

 *

 * Return:	0 on success or error code in case of error
@@ -148,7 +150,7 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes, 
	unsigned int n = mpi_get_size(a);

	int i, lzeros = 0;



	if (buf_len < n || !buf || !nbytes)

	if (!buf || !nbytes)

		return -EINVAL;



	if (sign)
@@ -163,6 +165,11 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes, 
			break;

	}



	if (buf_len < n - lzeros) {

		*nbytes = n - lzeros;

		return -EOVERFLOW;

	}



	p = buf;

	*nbytes = n - lzeros;
@@ -332,7 +339,8 @@ EXPORT_SYMBOL_GPL(mpi_set_buffer); 
 * @nbytes:	in/out param - it has the be set to the maximum number of

 *		bytes that can be written to sgl. This has to be at least

 *		the size of the integer a. On return it receives the actual

 *		length of the data written.

 *		length of the data written on success or the data that would

 *		be written if buffer was too small.

 * @sign:	if not NULL, it will be set to the sign of a.

 *

 * Return:	0 on success or error code in case of error
@@ -345,7 +353,7 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, 
	unsigned int n = mpi_get_size(a);

	int i, x, y = 0, lzeros = 0, buf_len;



	if (!nbytes || *nbytes < n)

	if (!nbytes)

		return -EINVAL;



	if (sign)
@@ -360,6 +368,11 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, 
			break;

	}



	if (*nbytes < n - lzeros) {

		*nbytes = n - lzeros;

		return -EOVERFLOW;

	}



	*nbytes = n - lzeros;

	buf_len = sgl->length;

	p2 = sg_virt(sgl);