Re: [PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is_registered
From: Josh Poimboeuf <hidden>
Date: 2018-07-29 13:59:22
Also in:
lkml, stable
On Fri, Jul 27, 2018 at 10:43:02PM +0000, Jeremy Cline wrote:
quoted hunk ↗ jump to hunk
'family' can be a user-controlled value, so sanitize it after the bounds check to avoid speculative out-of-bounds access. Cc: Josh Poimboeuf <redacted> Cc: stable@vger.kernel.org Signed-off-by: Jeremy Cline <redacted> --- 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