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@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
> ---
> 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
