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Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/…
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…linux/kernel/git/tip/tip

Pull core fixes from Ingo Molnar:
 "This fixes a particularly thorny munmap() bug with MPX, plus fixes a
  host build environment assumption in objtool"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Allow AR to be overridden with HOSTAR
  x86/mpx, mm/core: Fix recursive munmap() corruption
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@torvalds
torvalds committed May 19, 2019
2 parents 4c4a5c9 + 8ea58f1 commit 1335d9a
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Showing 9 changed files with 27 additions and 26 deletions.
1 change: 0 additions & 1 deletion arch/powerpc/include/asm/mmu_context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,6 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
extern void arch_exit_mmap(struct mm_struct *mm);

static inline void arch_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
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1 change: 0 additions & 1 deletion arch/um/include/asm/mmu_context.h
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Expand Up @@ -22,7 +22,6 @@ static inline int arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
}
extern void arch_exit_mmap(struct mm_struct *mm);
static inline void arch_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
}
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1 change: 0 additions & 1 deletion arch/unicore32/include/asm/mmu_context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,6 @@ static inline int arch_dup_mmap(struct mm_struct *oldmm,
}

static inline void arch_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
}
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6 changes: 3 additions & 3 deletions arch/x86/include/asm/mmu_context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -278,8 +278,8 @@ static inline void arch_bprm_mm_init(struct mm_struct *mm,
mpx_mm_init(mm);
}

static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long start, unsigned long end)
static inline void arch_unmap(struct mm_struct *mm, unsigned long start,
unsigned long end)
{
/*
* mpx_notify_unmap() goes and reads a rarely-hot
Expand All @@ -299,7 +299,7 @@ static inline void arch_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
* consistently wrong.
*/
if (unlikely(cpu_feature_enabled(X86_FEATURE_MPX)))
mpx_notify_unmap(mm, vma, start, end);
mpx_notify_unmap(mm, start, end);
}

/*
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15 changes: 8 additions & 7 deletions arch/x86/include/asm/mpx.h
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Expand Up @@ -64,12 +64,15 @@ struct mpx_fault_info {
};

#ifdef CONFIG_X86_INTEL_MPX
int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs);
int mpx_handle_bd_fault(void);

extern int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs);
extern int mpx_handle_bd_fault(void);

static inline int kernel_managing_mpx_tables(struct mm_struct *mm)
{
return (mm->context.bd_addr != MPX_INVALID_BOUNDS_DIR);
}

static inline void mpx_mm_init(struct mm_struct *mm)
{
/*
Expand All @@ -78,11 +81,10 @@ static inline void mpx_mm_init(struct mm_struct *mm)
*/
mm->context.bd_addr = MPX_INVALID_BOUNDS_DIR;
}
void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long start, unsigned long end);

unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len,
unsigned long flags);
extern void mpx_notify_unmap(struct mm_struct *mm, unsigned long start, unsigned long end);
extern unsigned long mpx_unmapped_area_check(unsigned long addr, unsigned long len, unsigned long flags);

#else
static inline int mpx_fault_info(struct mpx_fault_info *info, struct pt_regs *regs)
{
Expand All @@ -100,7 +102,6 @@ static inline void mpx_mm_init(struct mm_struct *mm)
{
}
static inline void mpx_notify_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
}
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10 changes: 6 additions & 4 deletions arch/x86/mm/mpx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -881,9 +881,10 @@ static int mpx_unmap_tables(struct mm_struct *mm,
* the virtual address region start...end have already been split if
* necessary, and the 'vma' is the first vma in this range (start -> end).
*/
void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long start, unsigned long end)
void mpx_notify_unmap(struct mm_struct *mm, unsigned long start,
unsigned long end)
{
struct vm_area_struct *vma;
int ret;

/*
Expand All @@ -902,11 +903,12 @@ void mpx_notify_unmap(struct mm_struct *mm, struct vm_area_struct *vma,
* which should not occur normally. Being strict about it here
* helps ensure that we do not have an exploitable stack overflow.
*/
do {
vma = find_vma(mm, start);
while (vma && vma->vm_start < end) {
if (vma->vm_flags & VM_MPX)
return;
vma = vma->vm_next;
} while (vma && vma->vm_start < end);
}

ret = mpx_unmap_tables(mm, start, end);
if (ret)
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1 change: 0 additions & 1 deletion include/asm-generic/mm_hooks.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ static inline void arch_exit_mmap(struct mm_struct *mm)
}

static inline void arch_unmap(struct mm_struct *mm,
struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
}
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15 changes: 8 additions & 7 deletions mm/mmap.c
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Expand Up @@ -2735,9 +2735,17 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
return -EINVAL;

len = PAGE_ALIGN(len);
end = start + len;
if (len == 0)
return -EINVAL;

/*
* arch_unmap() might do unmaps itself. It must be called
* and finish any rbtree manipulation before this code
* runs and also starts to manipulate the rbtree.
*/
arch_unmap(mm, start, end);

/* Find the first overlapping VMA */
vma = find_vma(mm, start);
if (!vma)
Expand All @@ -2746,7 +2754,6 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
/* we have start < vma->vm_end */

/* if it doesn't overlap, we have nothing.. */
end = start + len;
if (vma->vm_start >= end)
return 0;

Expand Down Expand Up @@ -2816,12 +2823,6 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
/* Detach vmas from rbtree */
detach_vmas_to_be_unmapped(mm, vma, prev, end);

/*
* mpx unmap needs to be called with mmap_sem held for write.
* It is safe to call it before unmap_region().
*/
arch_unmap(mm, vma, start, end);

if (downgrade)
downgrade_write(&mm->mmap_sem);

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3 changes: 2 additions & 1 deletion tools/objtool/Makefile
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Expand Up @@ -7,11 +7,12 @@ ARCH := x86
endif

# always use the host compiler
HOSTAR ?= ar
HOSTCC ?= gcc
HOSTLD ?= ld
AR = $(HOSTAR)
CC = $(HOSTCC)
LD = $(HOSTLD)
AR = ar

ifeq ($(srctree),)
srctree := $(patsubst %/,%,$(dir $(CURDIR)))
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