[ 3.5.y.z extended stable ] Patch "x86/efi: Fix dummy variable buffer allocation" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    x86/efi: Fix dummy variable buffer allocation

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From c3ab1bb3204f32e013aa58192e7ddf7562191137 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben at decadent.org.uk>
Date: Sun, 16 Jun 2013 21:27:12 +0100
Subject: [PATCH] x86/efi: Fix dummy variable buffer allocation

commit b8cb62f82103083a6e8fa5470bfe634a2c06514d upstream.

1. Check for allocation failure
2. Clear the buffer contents, as they may actually be written to flash
3. Don't leak the buffer

Compile-tested only.

[ Tested successfully on my buggy ASUS machine - Matt ]

Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
Signed-off-by: Matt Fleming <matt.fleming at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 2c990b5..ca4e1ad 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -1024,7 +1024,10 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 		 * that by attempting to use more space than is available.
 		 */
 		unsigned long dummy_size = remaining_size + 1024;
-		void *dummy = kmalloc(dummy_size, GFP_ATOMIC);
+		void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
+
+		if (!dummy)
+			return EFI_OUT_OF_RESOURCES;

 		status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
 					  EFI_VARIABLE_NON_VOLATILE |
@@ -1044,6 +1047,8 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 					 0, dummy);
 		}

+		kfree(dummy);
+
 		/*
 		 * The runtime code may now have triggered a garbage collection
 		 * run, so check the variable info again
--
1.8.1.2