* grub-core/lib/reed_solomon.c (grub_reed_solomon_recover): Don't do

Reed-Solomon recovery if more than half of redundancy info is 0.

ChangeLog

@@ -1,3 +1,8 @@
+2013-11-02  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	* grub-core/lib/reed_solomon.c (grub_reed_solomon_recover): Don't do
+	Reed-Solomon recovery if more than half of redundancy info is 0.
+
 2013-11-02  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	* util/grub-mount.c: Handle symlinks to directories.

grub-core/lib/reed_solomon.c

@@ -382,11 +382,18 @@ grub_reed_solomon_recover (void *ptr_, grub_size_t s, grub_size_t rs)
 {
   gf_single_t *ptr = ptr_;
   gf_single_t *rptr = ptr + s;
+  grub_uint8_t *cptr;
 
   /* Nothing to do.  */
   if (!rs)
     return;
 
+  for (cptr = rptr + rs - 1; cptr >= rptr; cptr--)
+    if (*cptr)
+      break;
+  if (rptr + rs - 1 - cptr > (grub_ssize_t) rs / 2)
+    return;
+
   init_powx ();
 
   while (s > 0)