[patch 38/45] x86: fix 64k corruption-check

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: Yinghai Lu <yinghai@xxxxxxxxxx>

upstream commit: 6d7942dc2a70a7e74c352107b150265602671588

Impact: fix boot crash

Need to exit early if the addr is far above 64k.

The crash got exposed by:

  78a8b35: x86: make e820_update_range() handle small range update

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
LKML-Reference: <49BC2279.2030101@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 arch/x86/kernel/check.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/check.c
+++ b/arch/x86/kernel/check.c
@@ -86,12 +86,12 @@ void __init setup_bios_corruption_check(
 		if (addr == 0)
 			break;
 
+		if (addr >= corruption_check_size)
+			break;
+
 		if ((addr + size) > corruption_check_size)
 			size = corruption_check_size - addr;
 
-		if (size == 0)
-			break;
-
 		e820_update_range(addr, size, E820_RAM, E820_RESERVED);
 		scan_areas[num_scan_areas].addr = addr;
 		scan_areas[num_scan_areas].size = size;

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