This is a note to let you know that I've just added the patch titled
lib/mpi: mpi_write_sgl(): fix skipping of leading zero limbs
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
lib-mpi-mpi_write_sgl-fix-skipping-of-leading-zero-limbs.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f2d1362ff7d266b3d2b1c764d6c2ef4a3b457f23 Mon Sep 17 00:00:00 2001
From: Nicolai Stange <nicstange@xxxxxxxxx>
Date: Tue, 22 Mar 2016 13:12:35 +0100
Subject: lib/mpi: mpi_write_sgl(): fix skipping of leading zero limbs
From: Nicolai Stange <nicstange@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
lib/mpi/mpicoder.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -367,7 +367,9 @@ int mpi_write_to_sgl(MPI a, struct scatt
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 scatt
#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);
}
Patches currently in stable-queue which might be from nicstange@xxxxxxxxx are
queue-4.4/lib-mpi-mpi_write_sgl-fix-skipping-of-leading-zero-limbs.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html