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| author | Nicolai Stange <nicstange@gmail.com> | 2016-03-22 15:12:35 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-15 09:27:54 +0300 |
| commit | 11c27e850d90372d79c1337be299923b5fb353e8 (patch) | |
| tree | 068c6da3a091106169bf63ed1e472a165adf7c21 /lib | |
| parent | 3838b04f6d5868f5ec5ee52ce1391b6253c6ce16 (diff) | |
| download | linux-11c27e850d90372d79c1337be299923b5fb353e8.tar.xz | |
lib/mpi: mpi_write_sgl(): fix skipping of leading zero limbs
commit f2d1362ff7d266b3d2b1c764d6c2ef4a3b457f23 upstream.
Currently, if the number of leading zeros is greater than fits into a
complete limb, mpi_write_sgl() skips them by iterating over them limb-wise.
However, it fails to adjust its internal leading zeros tracking variable,
lzeros, accordingly: it does a
p -= sizeof(alimb);
continue;
which should really have been a
lzeros -= sizeof(alimb);
continue;
Since lzeros never decreases if its initial value >= sizeof(alimb), nothing
gets copied by mpi_write_sgl() in that case.
Instead of skipping the high order zero limbs within the loop as shown
above, fix the issue by adjusting the copying loop's bounds.
Fixes: 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers")
Signed-off-by: Nicolai Stange <nicstange@gmail.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 | 21 |
1 files changed, 9 insertions, 12 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c index e00ff00e861c..e37dbf53e226 100644 --- a/lib/mpi/mpicoder.c +++ b/lib/mpi/mpicoder.c @@ -367,7 +367,9 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, buf_len = sgl->length; p2 = sg_virt(sgl); - for (i = a->nlimbs - 1; i >= 0; i--) { + for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB, + lzeros %= BYTES_PER_MPI_LIMB; + i >= 0; i--) { alimb = a->d[i]; p = (u8 *)&alimb2; #if BYTES_PER_MPI_LIMB == 4 @@ -388,17 +390,12 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes, #error please implement for this limb size. #endif if (lzeros > 0) { - if (lzeros >= sizeof(alimb)) { - p -= sizeof(alimb); - continue; - } else { - mpi_limb_t *limb1 = (void *)p - sizeof(alimb); - mpi_limb_t *limb2 = (void *)p - sizeof(alimb) - + lzeros; - *limb1 = *limb2; - p -= lzeros; - y = lzeros; - } + mpi_limb_t *limb1 = (void *)p - sizeof(alimb); + mpi_limb_t *limb2 = (void *)p - sizeof(alimb) + + lzeros; + *limb1 = *limb2; + p -= lzeros; + y = lzeros; lzeros -= sizeof(alimb); } |