| Message ID | 1318601457-4304-2-git-send-email-paolo.pisati@canonical.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Oct 14, 2011 at 04:10:57PM +0200, Paolo Pisati wrote: > From: Andrea Arcangeli <aarcange@redhat.com> > > CVE-2011-2479 > > BugLink: http://bugs.launchpad.net/bugs/775809 > > commit 78f11a255749d09025f54d4e2df4fbcb031530e2 upstream. > > The huge_memory.c THP page fault was allowed to run if vm_ops was null > (which would succeed for /dev/zero MAP_PRIVATE, as the f_op->mmap wouldn't > setup a special vma->vm_ops and it would fallback to regular anonymous > memory) but other THP logics weren't fully activated for vmas with vm_file > not NULL (/dev/zero has a not NULL vma->vm_file). > > So this removes the vm_file checks so that /dev/zero also can safely use > THP (the other albeit safer approach to fix this bug would have been to > prevent the THP initial page fault to run if vm_file was set). > > After removing the vm_file checks, this also makes huge_memory.c stricter > in khugepaged for the DEBUG_VM=y case. It doesn't replace the vm_file > check with a is_pfn_mapping check (but it keeps checking for VM_PFNMAP > under VM_BUG_ON) because for a is_cow_mapping() mapping VM_PFNMAP should > only be allowed to exist before the first page fault, and in turn when > vma->anon_vma is null (so preventing khugepaged registration). So I tend > to think the previous comment saying if vm_file was set, VM_PFNMAP might > have been set and we could still be registered in khugepaged (despite > anon_vma was not NULL to be registered in khugepaged) was too paranoid. > The is_linear_pfn_mapping check is also I think superfluous (as described > by comment) but under DEBUG_VM it is safe to stay. > > Addresses https://bugzilla.kernel.org/show_bug.cgi?id=33682 > > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> > Reported-by: Caspar Zhang <bugs@casparzhang.com> > Acked-by: Mel Gorman <mel@csn.ul.ie> > Acked-by: Rik van Riel <riel@redhat.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> > Signed-off-by: Tim Gardner <tim.gardner@canonical.com> <blank space> > (cherry picked from commit 3a7ecd0f369bc80f3647941224c3c24b7dcb9621) Signed-off-by: ?? > --- > include/linux/huge_mm.h | 2 +- > include/linux/mm.h | 3 ++- > mm/huge_memory.c | 43 ++++++++++++++++++++++++------------------- > 3 files changed, 27 insertions(+), 21 deletions(-) > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > index df29c8f..8847c8c 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -117,7 +117,7 @@ static inline void vma_adjust_trans_huge(struct vm_area_struct *vma, > unsigned long end, > long adjust_next) > { > - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) > + if (!vma->anon_vma || vma->vm_ops) > return; > __vma_adjust_trans_huge(vma, start, end, adjust_next); > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 4e43460..72674d4 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -137,7 +137,8 @@ extern unsigned int kobjsize(const void *objp); > #define VM_RandomReadHint(v) ((v)->vm_flags & VM_RAND_READ) > > /* > - * special vmas that are non-mergable, non-mlock()able > + * Special vmas that are non-mergable, non-mlock()able. > + * Note: mm/huge_memory.c VM_NO_THP depends on this definition. > */ > #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 8f76561..56cac93 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1400,6 +1400,9 @@ out: > return ret; > } > > +#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \ > + VM_HUGETLB|VM_SHARED|VM_MAYSHARE) > + > int hugepage_madvise(struct vm_area_struct *vma, > unsigned long *vm_flags, int advice) > { > @@ -1408,11 +1411,7 @@ int hugepage_madvise(struct vm_area_struct *vma, > /* > * Be somewhat over-protective like KSM for now! > */ > - if (*vm_flags & (VM_HUGEPAGE | > - VM_SHARED | VM_MAYSHARE | > - VM_PFNMAP | VM_IO | VM_DONTEXPAND | > - VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | > - VM_MIXEDMAP | VM_SAO)) > + if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) > return -EINVAL; > *vm_flags &= ~VM_NOHUGEPAGE; > *vm_flags |= VM_HUGEPAGE; > @@ -1428,11 +1427,7 @@ int hugepage_madvise(struct vm_area_struct *vma, > /* > * Be somewhat over-protective like KSM for now! > */ > - if (*vm_flags & (VM_NOHUGEPAGE | > - VM_SHARED | VM_MAYSHARE | > - VM_PFNMAP | VM_IO | VM_DONTEXPAND | > - VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | > - VM_MIXEDMAP | VM_SAO)) > + if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) > return -EINVAL; > *vm_flags &= ~VM_HUGEPAGE; > *vm_flags |= VM_NOHUGEPAGE; > @@ -1566,10 +1561,14 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma) > * page fault if needed. > */ > return 0; > - if (vma->vm_file || vma->vm_ops) > + if (vma->vm_ops) > /* khugepaged not yet working on file or special mappings */ > return 0; > - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); > + /* > + * If is_pfn_mapping() is true is_learn_pfn_mapping() must be > + * true too, verify it here. > + */ > + VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); > hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; > hend = vma->vm_end & HPAGE_PMD_MASK; > if (hstart < hend) > @@ -1818,12 +1817,15 @@ static void collapse_huge_page(struct mm_struct *mm, > (vma->vm_flags & VM_NOHUGEPAGE)) > goto out; > > - /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ > - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) > + if (!vma->anon_vma || vma->vm_ops) > goto out; > if (is_vma_temporary_stack(vma)) > goto out; > - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); > + /* > + * If is_pfn_mapping() is true is_learn_pfn_mapping() must be > + * true too, verify it here. > + */ > + VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); > > pgd = pgd_offset(mm, address); > if (!pgd_present(*pgd)) > @@ -2056,13 +2058,16 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, > progress++; > continue; > } > - /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ > - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) > + if (!vma->anon_vma || vma->vm_ops) > goto skip; > if (is_vma_temporary_stack(vma)) > goto skip; > - > - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); > + /* > + * If is_pfn_mapping() is true is_learn_pfn_mapping() > + * must be true too, verify it here. > + */ > + VM_BUG_ON(is_linear_pfn_mapping(vma) || > + vma->vm_flags & VM_NO_THP); > > hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; > hend = vma->vm_end & HPAGE_PMD_MASK; Other than the attribution this looks fine. Acked-by: Andy Whitcroft <apw@canonical.com> -apw
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index df29c8f..8847c8c 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -117,7 +117,7 @@ static inline void vma_adjust_trans_huge(struct vm_area_struct *vma, unsigned long end, long adjust_next) { - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) + if (!vma->anon_vma || vma->vm_ops) return; __vma_adjust_trans_huge(vma, start, end, adjust_next); } diff --git a/include/linux/mm.h b/include/linux/mm.h index 4e43460..72674d4 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -137,7 +137,8 @@ extern unsigned int kobjsize(const void *objp); #define VM_RandomReadHint(v) ((v)->vm_flags & VM_RAND_READ) /* - * special vmas that are non-mergable, non-mlock()able + * Special vmas that are non-mergable, non-mlock()able. + * Note: mm/huge_memory.c VM_NO_THP depends on this definition. */ #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8f76561..56cac93 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1400,6 +1400,9 @@ out: return ret; } +#define VM_NO_THP (VM_SPECIAL|VM_INSERTPAGE|VM_MIXEDMAP|VM_SAO| \ + VM_HUGETLB|VM_SHARED|VM_MAYSHARE) + int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice) { @@ -1408,11 +1411,7 @@ int hugepage_madvise(struct vm_area_struct *vma, /* * Be somewhat over-protective like KSM for now! */ - if (*vm_flags & (VM_HUGEPAGE | - VM_SHARED | VM_MAYSHARE | - VM_PFNMAP | VM_IO | VM_DONTEXPAND | - VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | - VM_MIXEDMAP | VM_SAO)) + if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP)) return -EINVAL; *vm_flags &= ~VM_NOHUGEPAGE; *vm_flags |= VM_HUGEPAGE; @@ -1428,11 +1427,7 @@ int hugepage_madvise(struct vm_area_struct *vma, /* * Be somewhat over-protective like KSM for now! */ - if (*vm_flags & (VM_NOHUGEPAGE | - VM_SHARED | VM_MAYSHARE | - VM_PFNMAP | VM_IO | VM_DONTEXPAND | - VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE | - VM_MIXEDMAP | VM_SAO)) + if (*vm_flags & (VM_NOHUGEPAGE | VM_NO_THP)) return -EINVAL; *vm_flags &= ~VM_HUGEPAGE; *vm_flags |= VM_NOHUGEPAGE; @@ -1566,10 +1561,14 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma) * page fault if needed. */ return 0; - if (vma->vm_file || vma->vm_ops) + if (vma->vm_ops) /* khugepaged not yet working on file or special mappings */ return 0; - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); + /* + * If is_pfn_mapping() is true is_learn_pfn_mapping() must be + * true too, verify it here. + */ + VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) @@ -1818,12 +1817,15 @@ static void collapse_huge_page(struct mm_struct *mm, (vma->vm_flags & VM_NOHUGEPAGE)) goto out; - /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) + if (!vma->anon_vma || vma->vm_ops) goto out; if (is_vma_temporary_stack(vma)) goto out; - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); + /* + * If is_pfn_mapping() is true is_learn_pfn_mapping() must be + * true too, verify it here. + */ + VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) @@ -2056,13 +2058,16 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, progress++; continue; } - /* VM_PFNMAP vmas may have vm_ops null but vm_file set */ - if (!vma->anon_vma || vma->vm_ops || vma->vm_file) + if (!vma->anon_vma || vma->vm_ops) goto skip; if (is_vma_temporary_stack(vma)) goto skip; - - VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma)); + /* + * If is_pfn_mapping() is true is_learn_pfn_mapping() + * must be true too, verify it here. + */ + VM_BUG_ON(is_linear_pfn_mapping(vma) || + vma->vm_flags & VM_NO_THP); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK;