mkfs: avoid out of bounds access to sb in wsect

e92fd614 · Russ Cox · 2ea6c764 · e92fd614
--- a/mkfs.c
+++ b/mkfs.c
@@ -90,7 +90,9 @@ main(int argc, char *argv[])
  for(i = 0; i < nblocks + usedblocks; i++)
    wsect(i, zeroes);

-  wsect(1, &sb);
+  memset(buf, 0, sizeof(buf));
+  memmove(buf, &sb, sizeof(sb));
+  wsect(1, buf);

  rootino = ialloc(T_DIR);
  assert(rootino == ROOTINO);