Messages in this thread | | | Subject | Re: [PATCH 12 of 20] ipath - misc driver support code | From | Arjan van de Ven <> | Date | Fri, 30 Dec 2005 19:15:47 +0100 |
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> +int ipath_get_upages_nocopy(unsigned long start_page, struct page **p) > +{ > + int n; > + struct vm_area_struct *vm = NULL; > + > + down_read(¤t->mm->mmap_sem); > + n = get_user_pages(current, current->mm, start_page, 1, 1, 1, p, &vm); > + up_read(¤t->mm->mmap_sem); > + if (n != 1) { > + _IPATH_INFO("get_user_pages for 0x%lx failed with %d\n", > + start_page, n); > + if (n < 0) /* it's an errno */ > + return n; > + /* > + * If we ever ask for more than a single page, we will have to > + * free the pages (if any) that we did get, via ipath_get_upages() > + * or put_page() directly. > + */ > + return -ENOMEM; /* no way to know actual error */ > + } > + vm->vm_flags |= VM_SHM | VM_LOCKED; > + > + return 0; > +}
I hope you're not depending on the VM_LOCKED thing.. since the user can just undo that easily!
(this is also why all this "sys_mlock from the driver" is traditionally buggy to the point of being a roothole, things like some of the binary 3D drivers have had this security hole for a long time, as did some of the early infiniband drivers)
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