On Tue, Feb 13, 2007 at 11:24:43PM +0100, Ingo Molnar wrote: > > > + memset(atom->args, 0, sizeof(atom->args)); > > > + > > > + ret |= __get_user(arg_ptr, &uatom->arg_ptr[0]); > > > + if (!arg_ptr) > > > + return ret; > > > + if (!access_ok(VERIFY_WRITE, arg_ptr, sizeof(*arg_ptr))) > > > + return -EFAULT; > > > > It's a little unclear why you do that many individual access_ok()s. > > And why is the target constant sized anyways? > > each indirect pointer has to be checked separately, before dereferencing > it. (Andrew pointed out that they should be VERIFY_READ, i fixed that in > my tree)
But why only constant sized? It could be a variable length object, couldn't it? If it's an array it could be all checked together (i must be missing something here) > > If it's only a few pages you don't need any resource accounting. If > > it's more then it's nasty to steal the users quota. I think plain > > gup() would be better. > > get_user_pages() would have to be limited in some way - and i didnt want If you only use it for a small ring buffer it is naturally limited. Also beancounter will fix that eventually. > a single page is enough for 1024 completion pointers - that's more than > enough for most purposes - and the default mlock limit is 40K. Then limit it to a single page and use gup -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
