diff options
Diffstat (limited to 'mm/mremap.c')
| -rw-r--r-- | mm/mremap.c | 43 |
1 files changed, 15 insertions, 28 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index e7ae140fc640..dda09e957a5d 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -238,6 +238,7 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr, { spinlock_t *old_ptl, *new_ptl; struct mm_struct *mm = vma->vm_mm; + bool res = false; pmd_t pmd; if (!arch_supports_page_table_move()) @@ -277,19 +278,25 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr, if (new_ptl != old_ptl) spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); - /* Clear the pmd */ pmd = *old_pmd; + + /* Racing with collapse? */ + if (unlikely(!pmd_present(pmd) || pmd_leaf(pmd))) + goto out_unlock; + /* Clear the pmd */ pmd_clear(old_pmd); + res = true; VM_BUG_ON(!pmd_none(*new_pmd)); pmd_populate(mm, new_pmd, pmd_pgtable(pmd)); flush_tlb_range(vma, old_addr, old_addr + PMD_SIZE); +out_unlock: if (new_ptl != old_ptl) spin_unlock(new_ptl); spin_unlock(old_ptl); - return true; + return res; } #else static inline bool move_normal_pmd(struct vm_area_struct *vma, @@ -902,19 +909,6 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len, if ((mm->map_count + 2) >= sysctl_max_map_count - 3) return -ENOMEM; - /* - * In mremap_to(). - * Move a VMA to another location, check if src addr is sealed. - * - * Place can_modify_mm here because mremap_to() - * does its own checking for address range, and we only - * check the sealing after passing those checks. - * - * can_modify_mm assumes we have acquired the lock on MM. - */ - if (unlikely(!can_modify_mm(mm, addr, addr + old_len))) - return -EPERM; - if (flags & MREMAP_FIXED) { /* * In mremap_to(). @@ -1052,6 +1046,12 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, goto out; } + /* Don't allow remapping vmas when they have already been sealed */ + if (!can_modify_vma(vma)) { + ret = -EPERM; + goto out; + } + if (is_vm_hugetlb_page(vma)) { struct hstate *h __maybe_unused = hstate_vma(vma); @@ -1080,19 +1080,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, } /* - * Below is shrink/expand case (not mremap_to()) - * Check if src address is sealed, if so, reject. - * In other words, prevent shrinking or expanding a sealed VMA. - * - * Place can_modify_mm here so we can keep the logic related to - * shrink/expand together. - */ - if (unlikely(!can_modify_mm(mm, addr, addr + old_len))) { - ret = -EPERM; - goto out; - } - - /* * Always allow a shrinking remap: that just unmaps * the unnecessary pages.. * do_vmi_munmap does all the needed commit accounting, and |