Commit bc5b6c0b authored Jul 31, 2018 by Jeremy Cline Committed by David S. Miller Aug 01, 2018

netlink: Fix spectre v1 gadget in netlink_create()



'protocol' is a user-controlled value, so sanitize it after the bounds
check to avoid using it for speculative out-of-bounds access to arrays
indexed by it.

This addresses the following accesses detected with the help of smatch:

* net/netlink/af_netlink.c:654 __netlink_create() warn: potential
  spectre issue 'nlk_cb_mutex_keys' [w]

* net/netlink/af_netlink.c:654 __netlink_create() warn: potential
  spectre issue 'nlk_cb_mutex_key_strings' [w]

* net/netlink/af_netlink.c:685 netlink_create() warn: potential spectre
  issue 'nl_table' [w] (local cap)

Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jeremy Cline <jcline@redhat.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e02ee981

net/netlink/af_netlink.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -63,6 +63,7 @@
		#include <linux/hash.h>
		#include <linux/genetlink.h>
		#include <linux/net_namespace.h>
		#include <linux/nospec.h>

		#include <net/net_namespace.h>
		#include <net/netns/generic.h>
		@@ -679,6 +680,7 @@ static int netlink_create(struct net net, struct socket sock, int protocol,

		if (protocol < 0 \|\| protocol >= MAX_LINKS)
		return -EPROTONOSUPPORT;
		protocol = array_index_nospec(protocol, MAX_LINKS);

		netlink_lock_table();
		#ifdef CONFIG_MODULES

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