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    SubjectRe: [PATCH v4] Added PR_SET_PROCTITLE_AREA option for prctl()
    > >+		case PR_SET_PROCTITLE_AREA: {
    > >+ struct mm_struct *mm = current->mm;
    > >+ unsigned long addr = arg2;
    > >+ unsigned long len = arg3;
    > >+ unsigned long end = arg2 + arg3;
    > >+
    > >+ if (len > PAGE_SIZE)
    > >+ return -EINVAL;
    > >+
    > >+ if (addr >= end)
    > >+ return -EINVAL;
    > >+
    > >+ if (!access_ok(VERIFY_READ, addr, len))
    > >+ return -EFAULT;
    > >+
    > >+ mutex_lock(&mm->arg_lock);
    > >+ mm->arg_start = addr;
    >
    > Is this safe? You're assigning a user-space pointer to kernel space...
    > Don't we need copy_from_user()?

    mm->arg_start, arg_end are defined so.
    Please see current implementation.


    > >+ mm->arg_end = addr + len;
    >
    > Since you already have 'end', no need to caculate this again. :)

    Good catch :)




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