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| author | Michal Marek <mmarek@suse.com> | 2016-02-17 14:46:59 +0100 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2016-02-28 03:26:30 +0800 |
| commit | 3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376 (patch) | |
| tree | 1e4d55e95009a958d84441ef97025c28f060ba72 /lib/mpi | |
| parent | bfd927ffa219ac81082b2dcc61a1c4037869befc (diff) | |
| download | linux-3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376.tar.gz linux-3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376.tar.bz2 linux-3ee0cb5fb5eea2110db1b5cb7f67029b7be8a376.zip | |
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')
| -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 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; |