From c76386454e2e2214c3082b26ab99f1e733cac5eb Mon Sep 17 00:00:00 2001
From: Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>
Date: Mon, 27 Dec 2010 07:09:43 +0100
Subject: [PATCH] 	Avoid using Reed-Solomon with 0 redundancy.

	* grub-core/kern/i386/pc/startup.S: Remove 0-data check.
	* grub-core/lib/reed_solomon.c (decode_block): Do not proceed on 0 data
	or 0 redundancy.
	(grub_reed_solomon_add_redundancy): Do not proceed with 0 redundancy.
	(grub_reed_solomon_recover): Likewise.
---
 ChangeLog                        | 10 ++++++++++
 grub-core/kern/i386/pc/startup.S |  2 --
 grub-core/lib/reed_solomon.c     | 16 ++++++++++++++--
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 0e4a725a5..d7606da2a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-12-27  Vladimir Serbinenko  <phcoder@gmail.com>
+
+	Avoid using Reed-Solomon with 0 redundancy.
+
+	* grub-core/kern/i386/pc/startup.S: Remove 0-data check.
+	* grub-core/lib/reed_solomon.c (decode_block): Do not proceed on 0 data
+	or 0 redundancy.
+	(grub_reed_solomon_add_redundancy): Do not proceed with 0 redundancy.
+	(grub_reed_solomon_recover): Likewise.
+
 2010-12-27  Vladimir Serbinenko  <phcoder@gmail.com>
 
 	Don't use disk subsystem in freebsd_boot.
diff --git a/grub-core/kern/i386/pc/startup.S b/grub-core/kern/i386/pc/startup.S
index 7aebc8b38..e78a0aa9a 100644
--- a/grub-core/kern/i386/pc/startup.S
+++ b/grub-core/kern/i386/pc/startup.S
@@ -151,8 +151,6 @@ LOCAL (codestart):
 	addl    $(GRUB_KERNEL_MACHINE_RAW_SIZE - GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART), %edx
 	movl    reed_solomon_redundancy, %ecx
 	leal    _start + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_PART, %eax
-	testl   %edx, %edx
-	jz post_reed_solomon
 	call    EXT_C (grub_reed_solomon_recover)
 	jmp post_reed_solomon
 
diff --git a/grub-core/lib/reed_solomon.c b/grub-core/lib/reed_solomon.c
index 6f571550a..9a40e2f98 100644
--- a/grub-core/lib/reed_solomon.c
+++ b/grub-core/lib/reed_solomon.c
@@ -372,6 +372,10 @@ decode_block (gf_single_t *ptr, grub_size_t s,
       grub_size_t rr = (rs + SECTOR_SIZE - 1 - i) / SECTOR_SIZE;
       gf_single_t m[ds + rr];
 
+      /* Nothing to do.  */
+      if (!ds || !rr)
+	continue;
+
       for (j = 0; j < (int) ds; j++)
 	m[j] = ptr[SECTOR_SIZE * j + i];
       for (j = 0; j < (int) rr; j++)
@@ -414,6 +418,10 @@ grub_reed_solomon_add_redundancy (void *buffer, grub_size_t data_size,
   gf_single_t *ptr = buffer;
   gf_single_t *rptr = ptr + s;
 
+  /* Nothing to do.  */
+  if (!rs)
+    return;
+
   while (s > 0)
     {
       grub_size_t tt;
@@ -441,6 +449,10 @@ 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;
 
+  /* Nothing to do.  */
+  if (!rs)
+    return;
+
 #if defined (STANDALONE)
   init_inverts ();
 #endif
@@ -454,8 +466,8 @@ grub_reed_solomon_recover (void *ptr_, grub_size_t s, grub_size_t rs)
       tt = cs + crs;
       if (tt > MAX_BLOCK_SIZE)
 	{
-	  cs = cs * MAX_BLOCK_SIZE / tt;
-	  crs = crs * MAX_BLOCK_SIZE / tt;
+	  cs = (cs * MAX_BLOCK_SIZE) / tt;
+	  crs = (crs * MAX_BLOCK_SIZE) / tt;
 	}
       decode_block (ptr, cs, rptr, crs);
       ptr += cs;