linux-kernel - [PATCH] x86, efi: initial the local variable of DataSize to zero

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Message-Id: <1367503621-13004-1-git-send-email-jlee@suse.com>
Date:	Thu,  2 May 2013 22:07:01 +0800
From:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
To:	matt.fleming@...el.com, mjg59@...f.ucam.org
Cc:	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Lee, Chun-Yi" <jlee@...e.com>, Matthew Garrett <mjg@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH] x86, efi: initial the local variable of DataSize to zero

That will be better initial the value of DataSize to zero for the input of
GetVariable(), otherwise we will feed a random value. The debug log of input
DataSize like this:

...
[  195.915612] EFI Variables Facility v0.08 2004-May-17
[  195.915819] efi: size: 18446744071581821342
[  195.915969] efi:  size': 18446744071581821342
[  195.916324] efi: size: 18446612150714306560
[  195.916632] efi:  size': 18446612150714306560
[  195.917159] efi: size: 18446612150714306560
[  195.917453] efi:  size': 18446612150714306560
...

The size' is value that was returned by BIOS.

After applied this patch:
[   82.442042] EFI Variables Facility v0.08 2004-May-17
[   82.442202] efi: size: 0
[   82.442360] efi:  size': 1039
[   82.443828] efi: size: 0
[   82.444127] efi:  size': 2616
[   82.447057] efi: size: 0
[   82.447356] efi:  size': 5832
...

Found on Acer Aspire V3 BIOS, it will not return the size of data if we input a
non-zero DataSize.

Cc: Matthew Garrett <mjg@...hat.com>
Cc: Matt Fleming <matt.fleming@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
---
 arch/x86/platform/efi/efi.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index e4a86a6..cb59732 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -204,7 +204,7 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 	}
 
 	if (boot_used_size && !finished) {
-		unsigned long size;
+		unsigned long size = 0;
 		u32 attr;
 		efi_status_t s;
 		void *tmp;
-- 
1.6.0.2

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