lkml.org 
[lkml]   [2018]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v9 08/24] mm: Protect VMA modifications using VMA sequence count
From
Date


On 27/03/2018 23:57, David Rientjes wrote:
> On Tue, 13 Mar 2018, Laurent Dufour wrote:
>
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index 5898255d0aeb..d6533cb85213 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -847,17 +847,18 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
>> }
>>
>> if (start != vma->vm_start) {
>> - vma->vm_start = start;
>> + WRITE_ONCE(vma->vm_start, start);
>> start_changed = true;
>> }
>> if (end != vma->vm_end) {
>> - vma->vm_end = end;
>> + WRITE_ONCE(vma->vm_end, end);
>> end_changed = true;
>> }
>> - vma->vm_pgoff = pgoff;
>> + WRITE_ONCE(vma->vm_pgoff, pgoff);
>> if (adjust_next) {
>> - next->vm_start += adjust_next << PAGE_SHIFT;
>> - next->vm_pgoff += adjust_next;
>> + WRITE_ONCE(next->vm_start,
>> + next->vm_start + (adjust_next << PAGE_SHIFT));
>> + WRITE_ONCE(next->vm_pgoff, next->vm_pgoff + adjust_next);
>> }
>>
>> if (root) {
>> @@ -1781,6 +1782,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>> out:
>> perf_event_mmap(vma);
>>
>> + vm_write_begin(vma);
>> vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
>> if (vm_flags & VM_LOCKED) {
>> if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
>> @@ -1803,6 +1805,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>> vma->vm_flags |= VM_SOFTDIRTY;
>>
>> vma_set_page_prot(vma);
>> + vm_write_end(vma);
>>
>> return addr;
>>
>
> Shouldn't this also protect vma->vm_flags?

Nice catch !
I just found that too while reviewing the entire patch to answer your previous
email.

>
> diff --git a/mm/mmap.c b/mm/mmap.c
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1796,7 +1796,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
> vma == get_gate_vma(current->mm)))
> mm->locked_vm += (len >> PAGE_SHIFT);
> else
> - vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
> + WRITE_ONCE(vma->vm_flags,
> + vma->vm_flags & VM_LOCKED_CLEAR_MASK);
> }
>
> if (file)
> @@ -1809,7 +1810,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
> * then new mapped in-place (which must be aimed as
> * a completely new data area).
> */
> - vma->vm_flags |= VM_SOFTDIRTY;
> + WRITE_ONCE(vma->vm_flags, vma->vm_flags | VM_SOFTDIRTY);
>
> vma_set_page_prot(vma);
> vm_write_end(vma);
>

\
 
 \ /
  Last update: 2018-03-28 19:11    [W:0.283 / U:0.264 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site