On Sun, Nov 09, 2014 at 09:19:08PM +0000, Al Viro wrote: > [Michael Cc'd] > > On Fri, Nov 07, 2014 at 11:42:53PM +0000, Al Viro wrote: > > > I'll finish RTFS drivers/vhost and if it turns out to be OK I'll post the > > series moving those checks to the moment of copying iovec from userland, > > so that kernel-side we could always rely on ->msg_iov elements having been > > verified. > > Two questions: > 1) does sparc64 access_ok() need to differ for 32bit and 64bit tasks? > AFAICS, x86 and ppc just check that address is OK for 64bit process - > if a 32bit process passes the kernel an address that would be valid > for 64bit process, but not for 32bit one, we just get a pagefault in > __copy_from_user() and friends. No kernel objects are going to have > a virtual address in that range, so access_ok() doesn't bother preventing > such access attempts there... > > 2) shouldn't vhost_dev_cleanup() stop the worker thread before doing anything > else? > AFAICS, we do parts of vhost_dev teardown while the thread is > still running; granted, we keep dev->mm pinned down until after it stops > (or we would be _really_ screwed), but is it safe to do all those fput()s, > etc. > while it's still running? Michael?
Before invoking vhost_dev_cleanup, the caller for vhost-net (vhost_net_release) sets private data to NULL (using vhost_net_stop_vq) which guarantees thread will do nothing at all. vhost scsi does it in vhost_scsi_clear_endpoint. -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
