[PATCH 92/98] x86,efi: Check max_size only if it is non-zero.

[Luis Henriques]

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

------------------

From: Richard Weinberger <richard@xxxxxx>

commit 7791c8423f1f7f4dad94e753bae67461d5b80be8 upstream.

Some EFI implementations return always a MaximumVariableSize of 0,
check against max_size only if it is non-zero.
My Intel DQ67SW desktop board has such an implementation.

Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 arch/x86/platform/efi/efi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index b8699b3..0eb3066 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -983,7 +983,12 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 	if (status != EFI_SUCCESS)
 		return status;
 
-	if (!storage_size || size > remaining_size || size > max_size ||
+	if (!max_size && remaining_size > size)
+		printk_once(KERN_ERR FW_BUG "Broken EFI implementation"
+			    " is returning MaxVariableSize=0\n");
+
+	if (!storage_size || size > remaining_size ||
+	    (max_size && size > max_size) ||
 	    (remaining_size - size) < (storage_size / 2))
 		return EFI_OUT_OF_RESOURCES;
 
-- 
1.8.1.2

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