linux-kernel - [PATCH] efi: Check EFI revision in setup_efi

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Date:	Wed, 24 Apr 2013 10:37:38 -0400
From:	Josh Boyer <jwboyer@...hat.com>
To:	Matthew Garrett <matthew.garrett@...ula.com>,
	Matt Fleming <matt.fleming@...el.com>
Cc:	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] efi: Check EFI revision in setup_efi_vars

We need to check the runtime sys_table for the EFI version the firmware
specifies instead of just checking for a NULL QueryVariableInfo.  Older
implementations of EFI don't have QueryVariableInfo but the runtime is
a smaller structure, so the pointer to it may be pointing off into garbage.

This is apparently the case with several Apple firmwares that support EFI
1.10, and the current check causes them to no longer boot.  Fix based on
a suggestion from Matthew Garrett.

Signed-off-by: Josh Boyer <jwboyer@...hat.com>
---
 arch/x86/boot/compressed/eboot.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 8615f75..b46efbf 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -258,7 +258,9 @@ static efi_status_t setup_efi_vars(struct boot_params *params)
 	u64 store_size, remaining_size, var_size;
 	efi_status_t status;
 
-	if (!sys_table->runtime->query_variable_info)
+	if (sys_table->runtime->hdr.revision < EFI_2_00_SYSTEM_TABLE_REVISION)
+		return EFI_UNSUPPORTED;
+	else if(!sys_table->runtime->query_variable_info)
 		return EFI_UNSUPPORTED;
 
 	data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
-- 
1.8.1.4

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