diff options
| author | Michal Marek <mmarek@suse.com> | 2016-02-17 14:46:59 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-04 14:48:51 -0700 |
| commit | 81b3a56ed84b0f2c1e2ff75ee2e05d5d4cd2462b (patch) | |
| tree | a4241143bc0a777aa4c3aa59ea7316ccd3e2da0c /lib | |
| parent | 0658e8c5e8cc02f12f9ae3df1f3b87ee7283bb24 (diff) | |
lib/mpi: Endianness fix
commit 3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/mpi/mpicoder.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c index 3db76b8c1115..e00ff00e861c 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) * @@ -146,7 +163,7 @@ 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_len < n || !buf || !nbytes) return -EINVAL; @@ -154,14 +171,7 @@ 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); p = buf; *nbytes = n - lzeros; @@ -343,7 +353,7 @@ 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 || *nbytes < n) return -EINVAL; @@ -351,14 +361,7 @@ 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); *nbytes = n - lzeros; buf_len = sgl->length; |