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 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.
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.
Thanks for the review!