4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dan Williams dan.j.williams@intel.com
commit 3968523f855050b8195134da951b87c20bd66130 upstream.
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: Dan Williams dan.j.williams@intel.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/mpls/af_mpls.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-)
--- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -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> @@ -904,24 +905,27 @@ errout: 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, @@ -944,7 +948,7 @@ static int mpls_route_add(struct mpls_ro 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 */ @@ -1021,7 +1025,7 @@ static int mpls_route_del(struct mpls_ro
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); @@ -1779,7 +1783,7 @@ static int rtm_to_route_config(struct sk goto errout;
if (!mpls_label_ok(cfg->rc_nlinfo.nl_net, - cfg->rc_label, extack)) + &cfg->rc_label, extack)) goto errout; break; } @@ -2106,7 +2110,7 @@ static int mpls_getroute(struct sk_buff goto errout; }
- if (!mpls_label_ok(net, in_label, extack)) { + if (!mpls_label_ok(net, &in_label, extack)) { err = -EINVAL; goto errout; }