[3.11.y.z extended stable] Patch "Revert "x86-64, modify_ldt: Make support for 16-bit segments a runtime option"" has been added to staging queue

[Luis Henriques]

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

    Revert "x86-64, modify_ldt: Make support for 16-bit segments a runtime option"

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From a2234ae557aa70b27a3f108fcc220d2499e21f08 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa at zytor.com>
Date: Wed, 21 May 2014 10:22:59 -0700
Subject: Revert "x86-64, modify_ldt: Make support for 16-bit segments a
 runtime option"

commit 7ed6fb9b5a5510e4ef78ab27419184741169978a upstream.

This reverts commit fa81511bb0bbb2b1aace3695ce869da9762624ff in
preparation of merging in the proper fix (espfix64).

Signed-off-by: H. Peter Anvin <hpa at zytor.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/kernel/ldt.c        | 4 +---
 arch/x86/vdso/vdso32-setup.c | 8 --------
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index dcbbaa165bde..af1d14a9ebda 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -20,8 +20,6 @@
 #include <asm/mmu_context.h>
 #include <asm/syscalls.h>

-int sysctl_ldt16 = 0;
-
 #ifdef CONFIG_SMP
 static void flush_ldt(void *current_mm)
 {
@@ -236,7 +234,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
 	 * IRET leaking the high bits of the kernel stack address.
 	 */
 #ifdef CONFIG_X86_64
-	if (!ldt_info.seg_32bit && !sysctl_ldt16) {
+	if (!ldt_info.seg_32bit) {
 		error = -EINVAL;
 		goto out_unlock;
 	}
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index f1d633a43f8e..d6bfb876cfb0 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -41,7 +41,6 @@ enum {
 #ifdef CONFIG_X86_64
 #define vdso_enabled			sysctl_vsyscall32
 #define arch_setup_additional_pages	syscall32_setup_pages
-extern int sysctl_ldt16;
 #endif

 /*
@@ -381,13 +380,6 @@ static struct ctl_table abi_table2[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{
-		.procname	= "ldt16",
-		.data		= &sysctl_ldt16,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec
-	},
 	{}
 };

--
1.9.1