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Commit 3968523f authored by Dan Williams's avatar Dan Williams Committed by David S. Miller
Browse files

mpls, nospec: Sanitize array index in mpls_label_ok() 



mpls_label_ok() validates that the 'platform_label' array index from a
userspace netlink message payload is valid. Under speculation the
mpls_label_ok() result may not resolve in the CPU pipeline until after
the index is used to access an array element. Sanitize the index to zero
to prevent userspace-controlled arbitrary out-of-bounds speculation, a
precursor for a speculative execution side channel vulnerability.

Cc: <stable@vger.kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ebeeb1ad

net/mpls/af_mpls.c

+14 −10
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/ipv6.h>

#include <linux/mpls.h>

#include <linux/netconf.h>

#include <linux/nospec.h>

#include <linux/vmalloc.h>

#include <linux/percpu.h>

#include <net/ip.h>
@@ -935,24 +936,27 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg, 
	return err;

}



static bool mpls_label_ok(struct net *net, unsigned int index,

static bool mpls_label_ok(struct net *net, unsigned int *index,

			  struct netlink_ext_ack *extack)

{

	bool is_ok = true;



	/* Reserved labels may not be set */

	if (index < MPLS_LABEL_FIRST_UNRESERVED) {

	if (*index < MPLS_LABEL_FIRST_UNRESERVED) {

		NL_SET_ERR_MSG(extack,

			       "Invalid label - must be MPLS_LABEL_FIRST_UNRESERVED or higher");

		return false;

		is_ok = false;

	}



	/* The full 20 bit range may not be supported. */

	if (index >= net->mpls.platform_labels) {

	if (is_ok && *index >= net->mpls.platform_labels) {

		NL_SET_ERR_MSG(extack,

			       "Label >= configured maximum in platform_labels");

		return false;

		is_ok = false;

	}



	return true;

	*index = array_index_nospec(*index, net->mpls.platform_labels);

	return is_ok;

}



static int mpls_route_add(struct mpls_route_config *cfg,
@@ -975,7 +979,7 @@ static int mpls_route_add(struct mpls_route_config *cfg, 
		index = find_free_label(net);

	}



	if (!mpls_label_ok(net, index, extack))

	if (!mpls_label_ok(net, &index, extack))

		goto errout;



	/* Append makes no sense with mpls */
@@ -1052,7 +1056,7 @@ static int mpls_route_del(struct mpls_route_config *cfg, 


	index = cfg->rc_label;



	if (!mpls_label_ok(net, index, extack))

	if (!mpls_label_ok(net, &index, extack))

		goto errout;



	mpls_route_update(net, index, NULL, &cfg->rc_nlinfo);
@@ -1810,7 +1814,7 @@ static int rtm_to_route_config(struct sk_buff *skb, 
				goto errout;



			if (!mpls_label_ok(cfg->rc_nlinfo.nl_net,

					   cfg->rc_label, extack))

					   &cfg->rc_label, extack))

				goto errout;

			break;

		}
@@ -2137,7 +2141,7 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh, 
			goto errout;

		}



		if (!mpls_label_ok(net, in_label, extack)) {

		if (!mpls_label_ok(net, &in_label, extack)) {

			err = -EINVAL;

			goto errout;

		}