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: Sun, 29 Jul 2018 08:59:06 -0500 Message-ID: <20180729135906.lgqo5ue6it3hl2da@treble> References: <20180727224302.5503-1-jcline@redhat.com> <20180727224302.5503-3-jcline@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: <20180727224302.5503-3-jcline@redhat.com> Sender: stable-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. -- Josh