unsigned long reason)
{
struct mm_struct *mm = ctx->mm;
- pte_t *pte;
+ pte_t *ptep, pte;
bool ret = true;
VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
- pte = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
- if (!pte)
+ ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma));
+
+ if (!ptep)
goto out;
ret = false;
+ pte = huge_ptep_get(ptep);
/*
* Lockless access: we're in a wait_event so it's ok if it
* changes under us.
*/
- if (huge_pte_none(*pte))
+ if (huge_pte_none(pte))
ret = true;
- if (!huge_pte_write(*pte) && (reason & VM_UFFD_WP))
+ if (!huge_pte_write(pte) && (reason & VM_UFFD_WP))
ret = true;
out:
return ret;
/* the various vma->vm_userfaultfd_ctx still points to it */
down_write(&mm->mmap_sem);
+ /* no task can run (and in turn coredump) yet */
+ VM_WARN_ON(!mmget_still_valid(mm));
for (vma = mm->mmap; vma; vma = vma->vm_next)
- if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx)
+ if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
+ vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
+ }
up_write(&mm->mmap_sem);
userfaultfd_ctx_put(release_new_ctx);
struct userfaultfd_ctx *ctx;
ctx = vma->vm_userfaultfd_ctx.ctx;
- if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
+
+ if (!ctx)
+ return;
+
+ if (ctx->features & UFFD_FEATURE_EVENT_REMAP) {
vm_ctx->ctx = ctx;
userfaultfd_ctx_get(ctx);
+ } else {
+ /* Drop uffd context if remap feature not enabled */
+ vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
+ vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING);
}
}
* taking the mmap_sem for writing.
*/
down_write(&mm->mmap_sem);
+ if (!mmget_still_valid(mm))
+ goto skip_mm;
prev = NULL;
for (vma = mm->mmap; vma; vma = vma->vm_next) {
cond_resched();
vma->vm_flags = new_flags;
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
}
+skip_mm:
up_write(&mm->mmap_sem);
mmput(mm);
wakeup:
goto out;
down_write(&mm->mmap_sem);
+ if (!mmget_still_valid(mm))
+ goto out_unlock;
vma = find_vma_prev(mm, start, &prev);
if (!vma)
goto out_unlock;
ret = -EINVAL;
if (!vma_can_userfault(cur))
goto out_unlock;
+
+ /*
+ * UFFDIO_COPY will fill file holes even without
+ * PROT_WRITE. This check enforces that if this is a
+ * MAP_SHARED, the process has write permission to the backing
+ * file. If VM_MAYWRITE is set it also enforces that on a
+ * MAP_SHARED vma: there is no F_WRITE_SEAL and no further
+ * F_WRITE_SEAL can be taken until the vma is destroyed.
+ */
+ ret = -EPERM;
+ if (unlikely(!(cur->vm_flags & VM_MAYWRITE)))
+ goto out_unlock;
+
/*
* If this vma contains ending address, and huge pages
* check alignment.
BUG_ON(!vma_can_userfault(vma));
BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
vma->vm_userfaultfd_ctx.ctx != ctx);
+ WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
/*
* Nothing to do: this vma is already registered into this
goto out;
down_write(&mm->mmap_sem);
+ if (!mmget_still_valid(mm))
+ goto out_unlock;
vma = find_vma_prev(mm, start, &prev);
if (!vma)
goto out_unlock;
if (!vma->vm_userfaultfd_ctx.ctx)
goto skip;
+ WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
+
if (vma->vm_start > start)
start = vma->vm_start;
vma_end = min(end, vma->vm_end);