Messages in this thread Patch in this message | | | Date | Sun, 29 Jul 2018 08:59:06 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is_registered |
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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 <jpoimboe@redhat.com> > Cc: stable@vger.kernel.org > Signed-off-by: Jeremy Cline <jcline@redhat.com> > --- > 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
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