diff options
Diffstat (limited to 'drivers/ptp/ptp_vmclock.c')
| -rw-r--r-- | drivers/ptp/ptp_vmclock.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/ptp/ptp_vmclock.c b/drivers/ptp/ptp_vmclock.c index 83114695dbb5..8edc2880c609 100644 --- a/drivers/ptp/ptp_vmclock.c +++ b/drivers/ptp/ptp_vmclock.c @@ -371,6 +371,12 @@ static int vmclock_miscdev_mmap(struct file *fp, struct vm_area_struct *vma) */ vm_flags_clear(vma, VM_MAYWRITE); + /* + * Restrict the read-only mapping so it cannot be upgraded to + * writable later with mprotect(). + */ + vm_flags_clear(vma, VM_MAYWRITE); + if (vma->vm_end - vma->vm_start != PAGE_SIZE || vma->vm_pgoff) return -EINVAL; |