From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: [PATCH net 1/2] netlink: add NLA_U8_BUGGY attribute type Date: Sat, 2 Dec 2017 15:48:36 -0700 Message-ID: References: <20171202202332.10205-1-johannes@sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: j@w1.fi, Johannes Berg To: Johannes Berg , linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <20171202202332.10205-1-johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org> Content-Language: en-US Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On 12/2/17 1:23 PM, Johannes Berg wrote: > From: Johannes Berg > > This netlink type is used only for backwards compatibility > with broken userspace that used the wrong size for a given > u8 attribute, which is now rejected. It would've been wrong > before already, since on big endian the wrong value (always > zero) would be used by the kernel, but we can't break the > existing deployed userspace - hostapd for example now fails > to initialize entirely. > > We could try to fix up the big endian problem here, but we > don't know *how* userspace misbehaved - if using nla_put_u32 > then we could, but we also found a debug tool (which we'll > ignore for the purposes of this regression) that was putting > the padding into the length. > > Fixes: 28033ae4e0f5 ("net: netlink: Update attr validation to require exact length for some types") > Signed-off-by: Johannes Berg Hi Johannes: I have been really busy the past 2 weeks, so have not gotten around to dealing with this. I was planning to partially revert 28033ae4e0f5 -- change it from failure to log an error message so buggy commands can be fixed. David