From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Dave Hansen <dave.hansen@linux.intel.com>
Date: Mon, 4 Dec 2017 17:25:07 -0800
Subject: [PATCH] x86/entry: Rename SYSENTER_stack to
 CPU_ENTRY_AREA_entry_stack
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CVE-2017-5754

If the kernel oopses while on the trampoline stack, it will print
"<SYSENTER>" even if SYSENTER is not involved.  That is rather confusing.

The "SYSENTER" stack is used for a lot more than SYSENTER now.  Give it a
better string to display in stack dumps, and rename the kernel code to
match.

Also move the 32-bit code over to the new naming even though it still uses
the entry stack only for SYSENTER.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 4fe2d8b11a370af286287a2661de9d4e6c9a145a)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
(cherry picked from commit e0437c473463f208c2b4952f0826e43ce1335a53)
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
 arch/x86/include/asm/fixmap.h     |  8 ++++----
 arch/x86/include/asm/processor.h  |  6 +++---
 arch/x86/include/asm/stacktrace.h |  4 ++--
 arch/x86/kernel/asm-offsets.c     |  4 ++--
 arch/x86/kernel/asm-offsets_32.c  |  2 +-
 arch/x86/kernel/cpu/common.c      | 14 +++++++-------
 arch/x86/kernel/dumpstack.c       | 10 +++++-----
 arch/x86/kernel/dumpstack_32.c    |  6 +++---
 arch/x86/kernel/dumpstack_64.c    | 12 +++++++++---
 arch/x86/entry/entry_32.S         | 12 ++++++------
 arch/x86/entry/entry_64.S         |  4 ++--
 11 files changed, 44 insertions(+), 38 deletions(-)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 5dc269ff4085..a7fb137ad964 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -56,10 +56,10 @@ struct cpu_entry_area {
 	char gdt[PAGE_SIZE];
 
 	/*
-	 * The GDT is just below SYSENTER_stack and thus serves (on x86_64) as
+	 * The GDT is just below entry_stack and thus serves (on x86_64) as
 	 * a a read-only guard page.
 	 */
-	struct SYSENTER_stack_page SYSENTER_stack_page;
+	struct entry_stack_page entry_stack_page;
 
 	/*
 	 * On x86_64, the TSS is mapped RO.  On x86_32, it's mapped RW because
@@ -230,9 +230,9 @@ static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
 	return (struct cpu_entry_area *)__fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
 }
 
-static inline struct SYSENTER_stack *cpu_SYSENTER_stack(int cpu)
+static inline struct entry_stack *cpu_entry_stack(int cpu)
 {
-	return &get_cpu_entry_area(cpu)->SYSENTER_stack_page.stack;
+	return &get_cpu_entry_area(cpu)->entry_stack_page.stack;
 }
 
 #endif /* !__ASSEMBLY__ */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 59a317f8e0ec..935d68609922 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -330,12 +330,12 @@ struct x86_hw_tss {
 #define IO_BITMAP_OFFSET		(offsetof(struct tss_struct, io_bitmap) - offsetof(struct tss_struct, x86_tss))
 #define INVALID_IO_BITMAP_OFFSET	0x8000
 
-struct SYSENTER_stack {
+struct entry_stack {
 	unsigned long		words[64];
 };
 
-struct SYSENTER_stack_page {
-	struct SYSENTER_stack stack;
+struct entry_stack_page {
+	struct entry_stack stack;
 } __aligned(PAGE_SIZE);
 
 struct tss_struct {
diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 95f999576131..3b3cc5ba579a 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -15,7 +15,7 @@ enum stack_type {
 	STACK_TYPE_TASK,
 	STACK_TYPE_IRQ,
 	STACK_TYPE_SOFTIRQ,
-	STACK_TYPE_SYSENTER,
+	STACK_TYPE_ENTRY,
 	STACK_TYPE_EXCEPTION,
 	STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1,
 };
@@ -28,7 +28,7 @@ struct stack_info {
 bool in_task_stack(unsigned long *stack, struct task_struct *task,
 		   struct stack_info *info);
 
-bool in_sysenter_stack(unsigned long *stack, struct stack_info *info);
+bool in_entry_stack(unsigned long *stack, struct stack_info *info);
 
 int get_stack_info(unsigned long *stack, struct task_struct *task,
 		   struct stack_info *info, unsigned long *visit_mask);
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 40c3fab107ac..25b4832e9c28 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -96,6 +96,6 @@ void common(void) {
 	/* Layout info for cpu_entry_area */
 	OFFSET(CPU_ENTRY_AREA_tss, cpu_entry_area, tss);
 	OFFSET(CPU_ENTRY_AREA_entry_trampoline, cpu_entry_area, entry_trampoline);
-	OFFSET(CPU_ENTRY_AREA_SYSENTER_stack, cpu_entry_area, SYSENTER_stack_page);
-	DEFINE(SIZEOF_SYSENTER_stack, sizeof(struct SYSENTER_stack));
+	OFFSET(CPU_ENTRY_AREA_entry_stack, cpu_entry_area, entry_stack_page);
+	DEFINE(SIZEOF_entry_stack, sizeof(struct entry_stack));
 }
diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c
index c4f23da7a0f0..4dba34cb777d 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -50,7 +50,7 @@ void foo(void)
 
 	/* Offset from the sysenter stack to tss.sp0 */
 	DEFINE(TSS_sysenter_sp0, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) -
-	       offsetofend(struct cpu_entry_area, SYSENTER_stack_page.stack));
+	       offsetofend(struct cpu_entry_area, entry_stack_page.stack));
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 	BLANK();
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fcdba90e0890..7a8a5d436566 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -487,8 +487,8 @@ static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
 	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
 #endif
 
-static DEFINE_PER_CPU_PAGE_ALIGNED(struct SYSENTER_stack_page,
-				   SYSENTER_stack_storage);
+static DEFINE_PER_CPU_PAGE_ALIGNED(struct entry_stack_page,
+				   entry_stack_storage);
 
 static void __init
 set_percpu_fixmap_pages(int idx, void *ptr, int pages, pgprot_t prot)
@@ -523,8 +523,8 @@ static void __init setup_cpu_entry_area(int cpu)
 #endif
 
 	__set_fixmap(get_cpu_entry_area_index(cpu, gdt), get_cpu_gdt_paddr(cpu), gdt_prot);
-	set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, SYSENTER_stack_page),
-				per_cpu_ptr(&SYSENTER_stack_storage, cpu), 1,
+	set_percpu_fixmap_pages(get_cpu_entry_area_index(cpu, entry_stack_page),
+				per_cpu_ptr(&entry_stack_storage, cpu), 1,
 				PAGE_KERNEL);
 
 	/*
@@ -1315,7 +1315,7 @@ void enable_sep_cpu(void)
 
 	tss->x86_tss.ss1 = __KERNEL_CS;
 	wrmsr(MSR_IA32_SYSENTER_CS, tss->x86_tss.ss1, 0);
-	wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1), 0);
+	wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_entry_stack(cpu) + 1), 0);
 	wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
 
 	put_cpu();
@@ -1441,7 +1441,7 @@ void syscall_init(void)
 	 * AMD doesn't allow SYSENTER in long mode (either 32- or 64-bit).
 	 */
 	wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
-	wrmsrl_safe(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
+	wrmsrl_safe(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_entry_stack(cpu) + 1));
 	wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
 #else
 	wrmsrl(MSR_CSTAR, (unsigned long)ignore_sysret);
@@ -1655,7 +1655,7 @@ void cpu_init(void)
 	 */
 	set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
 	load_TR_desc();
-	load_sp0((unsigned long)(cpu_SYSENTER_stack(cpu) + 1));
+	load_sp0((unsigned long)(cpu_entry_stack(cpu) + 1));
 
 	load_mm_ldt(&init_mm);
 
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index b005e5ef6738..55bf1c3b5319 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -43,9 +43,9 @@ bool in_task_stack(unsigned long *stack, struct task_struct *task,
 	return true;
 }
 
-bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
+bool in_entry_stack(unsigned long *stack, struct stack_info *info)
 {
-	struct SYSENTER_stack *ss = cpu_SYSENTER_stack(smp_processor_id());
+	struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
 
 	void *begin = ss;
 	void *end = ss + 1;
@@ -53,7 +53,7 @@ bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
 	if ((void *)stack < begin || (void *)stack >= end)
 		return false;
 
-	info->type	= STACK_TYPE_SYSENTER;
+	info->type	= STACK_TYPE_ENTRY;
 	info->begin	= begin;
 	info->end	= end;
 	info->next_sp	= NULL;
@@ -111,13 +111,13 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	 * - task stack
 	 * - interrupt stack
 	 * - HW exception stacks (double fault, nmi, debug, mce)
-	 * - SYSENTER stack
+	 * - entry stack
 	 *
 	 * x86-32 can have up to four stacks:
 	 * - task stack
 	 * - softirq stack
 	 * - hardirq stack
-	 * - SYSENTER stack
+	 * - entry stack
 	 */
 	for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
 		const char *stack_name;
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 3160bf2d100e..4580ba0204f6 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -25,8 +25,8 @@ const char *stack_type_name(enum stack_type type)
 	if (type == STACK_TYPE_SOFTIRQ)
 		return "SOFTIRQ";
 
-	if (type == STACK_TYPE_SYSENTER)
-		return "SYSENTER";
+	if (type == STACK_TYPE_ENTRY)
+		return "ENTRY_TRAMPOLINE";
 
 	return NULL;
 }
@@ -95,7 +95,7 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
 	if (task != current)
 		goto unknown;
 
-	if (in_sysenter_stack(stack, info))
+	if (in_entry_stack(stack, info))
 		goto recursion_check;
 
 	if (in_hardirq_stack(stack, info))
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index f5107b659f86..7d9c0e06afc2 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -36,8 +36,14 @@ const char *stack_type_name(enum stack_type type)
 	if (type == STACK_TYPE_IRQ)
 		return "IRQ";
 
-	if (type == STACK_TYPE_SYSENTER)
-		return "SYSENTER";
+	if (type == STACK_TYPE_ENTRY) {
+		/*
+		 * On 64-bit, we have a generic entry stack that we
+		 * use for all the kernel entry points, including
+		 * SYSENTER.
+		 */
+		return "ENTRY_TRAMPOLINE";
+	}
 
 	if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
 		return exception_stack_names[type - STACK_TYPE_EXCEPTION];
@@ -117,7 +123,7 @@ int get_stack_info(unsigned long *stack, struct task_struct *task,
 	if (in_irq_stack(stack, info))
 		goto recursion_check;
 
-	if (in_sysenter_stack(stack, info))
+	if (in_entry_stack(stack, info))
 		goto recursion_check;
 
 	goto unknown;
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 3ef7800007f8..634c6a78885c 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -949,9 +949,9 @@ ENTRY(debug)
 
 	/* Are we currently on the SYSENTER stack? */
 	movl	PER_CPU_VAR(cpu_entry_area), %ecx
-	addl	$CPU_ENTRY_AREA_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
-	subl	%eax, %ecx	/* ecx = (end of SYSENTER_stack) - esp */
-	cmpl	$SIZEOF_SYSENTER_stack, %ecx
+	addl	$CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx
+	subl	%eax, %ecx	/* ecx = (end of entry_stack) - esp */
+	cmpl	$SIZEOF_entry_stack, %ecx
 	jb	.Ldebug_from_sysenter_stack
 
 	TRACE_IRQS_OFF
@@ -993,9 +993,9 @@ ENTRY(nmi)
 
 	/* Are we currently on the SYSENTER stack? */
 	movl	PER_CPU_VAR(cpu_entry_area), %ecx
-	addl	$CPU_ENTRY_AREA_SYSENTER_stack + SIZEOF_SYSENTER_stack, %ecx
-	subl	%eax, %ecx	/* ecx = (end of SYSENTER_stack) - esp */
-	cmpl	$SIZEOF_SYSENTER_stack, %ecx
+	addl	$CPU_ENTRY_AREA_entry_stack + SIZEOF_entry_stack, %ecx
+	subl	%eax, %ecx	/* ecx = (end of entry_stack) - esp */
+	cmpl	$SIZEOF_entry_stack, %ecx
 	jb	.Lnmi_from_sysenter_stack
 
 	/* Not on SYSENTER stack. */
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 157860b3569f..03e052f02176 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -153,8 +153,8 @@ END(native_usergs_sysret64)
 	_entry_trampoline - CPU_ENTRY_AREA_entry_trampoline(%rip)
 
 /* The top word of the SYSENTER stack is hot and is usable as scratch space. */
-#define RSP_SCRATCH	CPU_ENTRY_AREA_SYSENTER_stack + \
-			SIZEOF_SYSENTER_stack - 8 + CPU_ENTRY_AREA
+#define RSP_SCRATCH	CPU_ENTRY_AREA_entry_stack + \
+			SIZEOF_entry_stack - 8 + CPU_ENTRY_AREA
 
 ENTRY(entry_SYSCALL_64_trampoline)
 	UNWIND_HINT_EMPTY
-- 
2.14.2

