From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Poimboeuf Subject: Re: [PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is_registered Date: Mon, 13 Aug 2018 12:16:42 -0500 Message-ID: <20180813171642.wlxmnzgsg2rkwe4o@treble> References: <20180727224302.5503-1-jcline@redhat.com> <20180727224302.5503-3-jcline@redhat.com> <20180729135906.lgqo5ue6it3hl2da@treble> <914d34af-ba80-93b9-6f17-413eef8bf210@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: "David S . Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org To: Jeremy Cline Return-path: Content-Disposition: inline In-Reply-To: <914d34af-ba80-93b9-6f17-413eef8bf210@redhat.com> Sender: stable-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Sun, Jul 29, 2018 at 11:59:36AM -0400, Jeremy Cline wrote: > On 07/29/2018 09:59 AM, Josh Poimboeuf wrote: > > On Fri, Jul 27, 2018 at 10:43:02PM +0000, Jeremy Cline wrote: > >> 'family' can be a user-controlled value, so sanitize it after the bounds > >> check to avoid speculative out-of-bounds access. > >> > >> Cc: Josh Poimboeuf > >> Cc: stable@vger.kernel.org > >> Signed-off-by: Jeremy Cline > >> --- > >> net/socket.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/net/socket.c b/net/socket.c > >> index f15d5cbb3ba4..608e29ae6baf 100644 > >> --- a/net/socket.c > >> +++ b/net/socket.c > >> @@ -2672,7 +2672,8 @@ EXPORT_SYMBOL(sock_unregister); > >> > >> bool sock_is_registered(int family) > >> { > >> - return family < NPROTO && rcu_access_pointer(net_families[family]); > >> + return family < NPROTO && > >> + rcu_access_pointer(net_families[array_index_nospec(family, NPROTO)]); > >> } > >> > >> static int __init sock_init(void) > > > > This is another one where I think it would be better to do the nospec > > clamp higher up the call chain. The untrusted 'family' value comes from > > __sock_diag_cmd(): > > > > __sock_diag_cmd > > sock_load_diag_module > > sock_is_registered > > > > That function has a bounds check, and also uses the value in some other > > array accesses: > > > > if (req->sdiag_family >= AF_MAX) > > return -EINVAL; > > > > if (sock_diag_handlers[req->sdiag_family] == NULL) > > sock_load_diag_module(req->sdiag_family, 0); > > > > mutex_lock(&sock_diag_table_mutex); > > hndl = sock_diag_handlers[req->sdiag_family]; > > ... > > > > So I think clamping 'req->sdiag_family' right after the bounds check > > would be the way to go. > > > > Indeed, the clamp there would cover this clamp. I had a scheme that I > quickly fix all the gadgets in functions with local comparisons, but > clearly that's going to result in call chains with multiple clamps. > > I can fix this in a follow-up with a clamp here, or respin this patch > set, whatever is easier for David. Hi Jeremy, Just checking up on this... since this patch was merged, will you be doing a followup patch? -- Josh