1 files changed, 25 insertions, 13 deletions

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index bc0a1da8afba..95c52a95259e 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -146,18 +146,25 @@ 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;
+        int i, lzeros = 0;
 
-        if (buf_len < n || !buf)
+        if (buf_len < n || !buf || !nbytes)
                 return -EINVAL;
 
         if (sign)
                 *sign = a->sign;
 
-        if (nbytes)
-                *nbytes = n;
+        p = (void *)&a->d[a->nlimbs] - 1;
+
+        for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
+                if (!*p)
+                        lzeros++;
+                else
+                        break;
+        }
 
         p = buf;
+        *nbytes = n - lzeros;
 
         for (i = a->nlimbs - 1; i >= 0; i--) {
                 alimb = a->d[i];
@@ -178,6 +185,19 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
 #else
 #error please implement for this limb size.
 #endif
+
+                if (lzeros > 0) {
+                        if (lzeros >= sizeof(alimb)) {
+                                p -= sizeof(alimb);
+                        } else {
+                                mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
+                                mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
+                                                        + lzeros;
+                                *limb1 = *limb2;
+                                p -= lzeros;
+                        }
+                        lzeros -= sizeof(alimb);
+                }
         }
         return 0;
 }
@@ -197,7 +217,7 @@ EXPORT_SYMBOL_GPL(mpi_read_buffer);
  */
 void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
 {
-        uint8_t *buf, *p;
+        uint8_t *buf;
         unsigned int n;
         int ret;
 
@@ -220,14 +240,6 @@ void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
                 kfree(buf);
                 return NULL;
         }
-
-        /* this is sub-optimal but we need to do the shift operation
-         * because the caller has to free the returned buffer */
-        for (p = buf; !*p && *nbytes; p++, --*nbytes)
-                ;
-        if (p != buf)
-                memmove(buf, p, *nbytes);
-
         return buf;
 }
 EXPORT_SYMBOL_GPL(mpi_get_buffer);