On Wed, 1 Sep 2021 08:22:42 +0000 David Laight wrote: > From: Jakub Kicinski > > Sent: 31 August 2021 17:30 > > > > On Thu, 26 Aug 2021 12:46:01 -0700 Peter Collingbourne wrote: > > > @@ -3306,6 +3308,8 @@ static int compat_ifr_data_ioctl(struct net *net, unsigned int cmd, > > > struct ifreq ifreq; > > > u32 data32; > > > > > > + if (!is_socket_ioctl_cmd(cmd)) > > > + return -ENOTTY; > > > if (copy_from_user(ifreq.ifr_name, u_ifreq32->ifr_name, IFNAMSIZ)) > > > return -EFAULT; > > > if (get_user(data32, &u_ifreq32->ifr_data)) > > > > Hi Peter, when resolving the net -> net-next merge conflict I couldn't > > figure out why this chunk is needed. It seems all callers of > > compat_ifr_data_ioctl() already made sure it's a socket IOCTL. > > Please double check my resolution (tip of net-next) and if this is > > indeed unnecessary perhaps send a cleanup? Thanks! > > 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.
