From: Vladimir Serbinenko <phcoder@gmail.com>
Date: Sat, 2 Nov 2013 20:28:03 +0000 (+0100)
Subject: 	* grub-core/lib/reed_solomon.c (grub_reed_solomon_recover): Don't do
X-Git-Tag: grub-2.02-beta1~511
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e25f8e1f372e0121d9f29107949cf323e833c832;p=thirdparty%2Fgrub.git

	* 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.
---

diff --git a/ChangeLog b/ChangeLog
index 4b3bec3df..5e75371a1 100644
--- a/ChangeLog
+++ b/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.
diff --git a/grub-core/lib/reed_solomon.c b/grub-core/lib/reed_solomon.c
index aecc1e278..51b58b8e2 100644
--- a/grub-core/lib/reed_solomon.c
+++ b/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)