On Wed, 1 Sep 2021 11:01:32 -0700 Peter Collingbourne wrote: > > > To stop the copy_from_user() faulting when the user buffer > > > isn't long enough. > > > In particular for iasatty() on arm with tagged pointers. > > > > Let me rephrase. is_socket_ioctl_cmd() is always true here. There were > > only two callers, both check cmd is of specific, "sockety" type. > > I see, it looks like we don't need the check on the compat path then. > > I can send a followup to clean this up but given that I got a comment > from another reviewer saying that we should try to make the native and > compat paths as similar as possible, maybe it isn't too bad to leave > things as is? I have a weak preference to get rid of it, the code is a little complex and extra dead code makes it harder to follow, but up to you. IMO the "right place" for the check is: static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) [...] default: /* --> here <-- */ err = sock_do_ioctl(net, sock, cmd, arg); break; Since that's the point where we take all the remaining cmd values and call a function which assumes struct ifreq. Compat code does not have a default statement. But as I said no big deal, feel free to ignore.
