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ARM: make vectors page inaccessible from userspace

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commit a5463cd3435475386cbbe7b06e01292ac169d36f upstream.

If kuser helpers are not provided by the kernel, disable user access to
the vectors page.  With the kuser helpers gone, there is no reason for
this page to be visible to userspace.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Russell King 2013-07-31 21:58:56 +01:00 committed by Greg Kroah-Hartman
parent a5510daad5
commit 75bc4446e0
3 changed files with 12 additions and 1 deletions
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2
arch/arm/include/asm/page.h
View file

@ -142,7 +142,9 @@ extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
extern void copy_page(void *to, const void *from);
#ifdef CONFIG_KUSER_HELPERS
#define __HAVE_ARCH_GATE_AREA 1
#endif
#ifdef CONFIG_ARM_LPAE
#include <asm/pgtable-3level-types.h>

7
arch/arm/kernel/process.c
View file

@ -433,6 +433,7 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
}
#ifdef CONFIG_MMU
#ifdef CONFIG_KUSER_HELPERS
/*
* The vectors page is always readable from user space for the
* atomic helpers. Insert it into the gate_vma so that it is visible
@ -465,10 +466,14 @@ int in_gate_area_no_mm(unsigned long addr)
{
return in_gate_area(NULL, addr);
}
#define is_gate_vma(vma) ((vma) = &gate_vma)
#else
#define is_gate_vma(vma) 0
#endif
const char *arch_vma_name(struct vm_area_struct *vma)
{
return (vma == &gate_vma) ? "[vectors]" :
return is_gate_vma(vma) ? "[vectors]" :
(vma->vm_mm && vma->vm_start == vma->vm_mm->context.sigpage) ?
"[sigpage]" : NULL;
}

4
arch/arm/mm/mmu.c
View file

@ -1220,7 +1220,11 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
map.pfn = __phys_to_pfn(virt_to_phys(vectors));
map.virtual = 0xffff0000;
map.length = PAGE_SIZE;
#ifdef CONFIG_KUSER_HELPERS
map.type = MT_HIGH_VECTORS;
#else
map.type = MT_LOW_VECTORS;
#endif
create_mapping(&map);
if (!vectors_high()) {