This is a note to let you know that I've just added the patch titled
x86: Require exact match for 'noxsave' command line option
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-require-exact-match-for-noxsave-command-line-option.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2cd3949f702692cf4c5d05b463f19cd706a92dd3 Mon Sep 17 00:00:00 2001
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Date: Tue, 11 Nov 2014 14:01:33 -0800
Subject: x86: Require exact match for 'noxsave' command line option
From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
commit 2cd3949f702692cf4c5d05b463f19cd706a92dd3 upstream.
We have some very similarly named command-line options:
arch/x86/kernel/cpu/common.c:__setup("noxsave", x86_xsave_setup);
arch/x86/kernel/cpu/common.c:__setup("noxsaveopt", x86_xsaveopt_setup);
arch/x86/kernel/cpu/common.c:__setup("noxsaves", x86_xsaves_setup);
__setup() is designed to match options that take arguments, like
"foo=bar" where you would have:
__setup("foo", x86_foo_func...);
The problem is that "noxsave" actually _matches_ "noxsaves" in
the same way that "foo" matches "foo=bar". If you boot an old
kernel that does not know about "noxsaves" with "noxsaves" on the
command line, it will interpret the argument as "noxsave", which
is not what you want at all.
This makes the "noxsave" handler only return success when it finds
an *exact* match.
[ tglx: We really need to make __setup() more robust. ]
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20141111220133.FE053984@xxxxxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/common.c | 2 ++
1 file changed, 2 insertions(+)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -146,6 +146,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
static int __init x86_xsave_setup(char *s)
{
+ if (strlen(s))
+ return 0;
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
setup_clear_cpu_cap(X86_FEATURE_XSAVES);
Patches currently in stable-queue which might be from dave.hansen@xxxxxxxxxxxxxxx are
queue-3.17/x86-require-exact-match-for-noxsave-command-line-option.patch
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