x86,efi: Check max_size only if it is non-zero.

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@nod.at>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Rui Xiang <rui.xiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0c121a4da31d700cda0ee86f91c7decc88693da8..bdc3ea4e89fab3a33ffa76ea31670fd9e4103e72 100644 (file)
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -979,7 +979,12 @@ 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;