98 lines
3.1 KiB
Diff
98 lines
3.1 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Andi Kleen <ak@linux.intel.com>
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Date: Fri, 13 Oct 2017 14:56:43 -0700
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Subject: [PATCH] x86/fpu: Parse clearcpuid= as early XSAVE argument
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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With a followon patch we want to make clearcpuid affect the XSAVE
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configuration. But xsave is currently initialized before arguments
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are parsed. Move the clearcpuid= parsing into the special
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early xsave argument parsing code.
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Since clearcpuid= contains a = we need to keep the old __setup
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around as a dummy, otherwise it would end up as a environment
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variable in init's environment.
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Signed-off-by: Andi Kleen <ak@linux.intel.com>
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Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Link: http://lkml.kernel.org/r/20171013215645.23166-4-andi@firstfloor.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit 0c2a3913d6f50503f7c59d83a6219e39508cc898)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 27deb452eb0d27c406f3817ab057201aa8767abe)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kernel/cpu/common.c | 16 +++++++---------
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arch/x86/kernel/fpu/init.c | 11 +++++++++++
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2 files changed, 18 insertions(+), 9 deletions(-)
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diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
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index 4be7b209a3d6..ef7b1ba56363 100644
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--- a/arch/x86/kernel/cpu/common.c
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+++ b/arch/x86/kernel/cpu/common.c
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@@ -1293,18 +1293,16 @@ void print_cpu_info(struct cpuinfo_x86 *c)
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pr_cont(")\n");
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}
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-static __init int setup_disablecpuid(char *arg)
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+/*
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+ * clearcpuid= was already parsed in fpu__init_parse_early_param.
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+ * But we need to keep a dummy __setup around otherwise it would
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+ * show up as an environment variable for init.
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+ */
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+static __init int setup_clearcpuid(char *arg)
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{
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- int bit;
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-
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- if (get_option(&arg, &bit) && bit >= 0 && bit < NCAPINTS * 32)
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- setup_clear_cpu_cap(bit);
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- else
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- return 0;
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-
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return 1;
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}
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-__setup("clearcpuid=", setup_disablecpuid);
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+__setup("clearcpuid=", setup_clearcpuid);
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#ifdef CONFIG_X86_64
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struct desc_ptr idt_descr __ro_after_init = {
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diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
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index d5d44c452624..07f0ab877f49 100644
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--- a/arch/x86/kernel/fpu/init.c
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+++ b/arch/x86/kernel/fpu/init.c
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@@ -249,6 +249,10 @@ static void __init fpu__init_system_ctx_switch(void)
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*/
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static void __init fpu__init_parse_early_param(void)
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{
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+ char arg[32];
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+ char *argptr = arg;
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+ int bit;
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+
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if (cmdline_find_option_bool(boot_command_line, "no387"))
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setup_clear_cpu_cap(X86_FEATURE_FPU);
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@@ -266,6 +270,13 @@ static void __init fpu__init_parse_early_param(void)
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if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
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setup_clear_cpu_cap(X86_FEATURE_XSAVES);
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+
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+ if (cmdline_find_option(boot_command_line, "clearcpuid", arg,
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+ sizeof(arg)) &&
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+ get_option(&argptr, &bit) &&
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+ bit >= 0 &&
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+ bit < NCAPINTS * 32)
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+ setup_clear_cpu_cap(bit);
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}
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/*
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--
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2.14.2
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