From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] rxrpc: Work around usercopy check Date: Fri, 16 Feb 2018 16:22:48 -0500 (EST) Message-ID: <20180216.162248.2136274977153072425.davem@davemloft.net> References: <151873554032.16545.2581958777736418547.stgit@warthog.procyon.org.uk> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org To: dhowells@redhat.com Return-path: In-Reply-To: <151873554032.16545.2581958777736418547.stgit@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: David Howells Date: Thu, 15 Feb 2018 22:59:00 +0000 > Due to a check recently added to copy_to_user(), it's now not permitted to > copy from slab-held data to userspace unless the slab is whitelisted. This > affects rxrpc_recvmsg() when it attempts to place an RXRPC_USER_CALL_ID > control message in the userspace control message buffer. A warning is > generated by usercopy_warn() because the source is the copy of the > user_call_ID retained in the rxrpc_call struct. > > Work around the issue by copying the user_call_ID to a variable on the > stack and passing that to put_cmsg(). > > The warning generated looks like: ... > Reported-by: Jonathan Billings > Signed-off-by: David Howells > Acked-by: Kees Cook > Tested-by: Jonathan Billings Applied, thanks David.