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authorMichal Marek <mmarek@suse.com>2016-02-17 14:46:59 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2016-02-28 03:26:30 +0800
commit3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376 (patch)
tree1e4d55e95009a958d84441ef97025c28f060ba72 /lib/mpi/mpicoder.c
parentbfd927ffa219ac81082b2dcc61a1c4037869befc (diff)
downloadlinux-stericsson-3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376.tar.gz
lib/mpi: Endianness fix
The limbs are integers in the host endianness, so we can't simply iterate over the individual bytes. The current code happens to work on little-endian, because the order of the limbs in the MPI array is the same as the order of the bytes in each limb, but it breaks on big-endian. Fixes: 0f74fbf77d45 ("MPI: Fix mpi_read_buffer") Signed-off-by: Michal Marek <mmarek@suse.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'lib/mpi/mpicoder.c')
-rw-r--r--lib/mpi/mpicoder.c39
1 files changed, 21 insertions, 18 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index ec533a6c77b5..eb15e7dc7b65 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -128,6 +128,23 @@ leave:
}
EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
+static int count_lzeros(MPI a)
+{
+ mpi_limb_t alimb;
+ int i, lzeros = 0;
+
+ for (i = a->nlimbs - 1; i >= 0; i--) {
+ alimb = a->d[i];
+ if (alimb == 0) {
+ lzeros += sizeof(mpi_limb_t);
+ } else {
+ lzeros += count_leading_zeros(alimb) / 8;
+ break;
+ }
+ }
+ return lzeros;
+}
+
/**
* mpi_read_buffer() - read MPI to a bufer provided by user (msb first)
*
@@ -148,7 +165,7 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
uint8_t *p;
mpi_limb_t alimb;
unsigned int n = mpi_get_size(a);
- int i, lzeros = 0;
+ int i, lzeros;
if (!buf || !nbytes)
return -EINVAL;
@@ -156,14 +173,7 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
if (sign)
*sign = a->sign;
- p = (void *)&a->d[a->nlimbs] - 1;
-
- for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
- if (!*p)
- lzeros++;
- else
- break;
- }
+ lzeros = count_lzeros(a);
if (buf_len < n - lzeros) {
*nbytes = n - lzeros;
@@ -351,7 +361,7 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
u8 *p, *p2;
mpi_limb_t alimb, alimb2;
unsigned int n = mpi_get_size(a);
- int i, x, y = 0, lzeros = 0, buf_len;
+ int i, x, y = 0, lzeros, buf_len;
if (!nbytes)
return -EINVAL;
@@ -359,14 +369,7 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
if (sign)
*sign = a->sign;
- p = (void *)&a->d[a->nlimbs] - 1;
-
- for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
- if (!*p)
- lzeros++;
- else
- break;
- }
+ lzeros = count_lzeros(a);
if (*nbytes < n - lzeros) {
*nbytes = n - lzeros;