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mpls, nospec: Sanitize array index in mpls_label_ok() 

commit 3968523f85 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>
pull/10/head
Dan Williams 2018-02-07 22:34:24 -08:00 committed by Greg Kroah-Hartman
parent 2949758414
commit 753fc48e59
1 changed files with 14 additions and 10 deletions
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24
net/mpls/af_mpls.c
View File

@ -8,6 +8,7 @@
#include <linux/ipv6.h> #include <linux/ipv6.h>
#include <linux/mpls.h> #include <linux/mpls.h>
#include <linux/netconf.h> #include <linux/netconf.h>
#include <linux/nospec.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/percpu.h> #include <linux/percpu.h>
#include <net/ip.h> #include <net/ip.h>
@ -904,24 +905,27 @@ errout:
return err; 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) struct netlink_ext_ack *extack)
{ {
bool is_ok = true;
/* Reserved labels may not be set */ /* Reserved labels may not be set */
if (index < MPLS_LABEL_FIRST_UNRESERVED) { if (*index < MPLS_LABEL_FIRST_UNRESERVED) {
NL_SET_ERR_MSG(extack, NL_SET_ERR_MSG(extack,
"Invalid label - must be MPLS_LABEL_FIRST_UNRESERVED or higher"); "Invalid label - must be MPLS_LABEL_FIRST_UNRESERVED or higher");
return false; is_ok = false;
} }
/* The full 20 bit range may not be supported. */ /* 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, NL_SET_ERR_MSG(extack,
"Label >= configured maximum in platform_labels"); "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, static int mpls_route_add(struct mpls_route_config *cfg,
@ -944,7 +948,7 @@ static int mpls_route_add(struct mpls_route_config *cfg,
index = find_free_label(net); index = find_free_label(net);
} }
if (!mpls_label_ok(net, index, extack)) if (!mpls_label_ok(net, &index, extack))
goto errout; goto errout;
/* Append makes no sense with mpls */ /* Append makes no sense with mpls */
@ -1021,7 +1025,7 @@ static int mpls_route_del(struct mpls_route_config *cfg,
index = cfg->rc_label; index = cfg->rc_label;
if (!mpls_label_ok(net, index, extack)) if (!mpls_label_ok(net, &index, extack))
goto errout; goto errout;
mpls_route_update(net, index, NULL, &cfg->rc_nlinfo); mpls_route_update(net, index, NULL, &cfg->rc_nlinfo);
@ -1779,7 +1783,7 @@ static int rtm_to_route_config(struct sk_buff *skb,
goto errout; goto errout;
if (!mpls_label_ok(cfg->rc_nlinfo.nl_net, if (!mpls_label_ok(cfg->rc_nlinfo.nl_net,
cfg->rc_label, extack)) &cfg->rc_label, extack))
goto errout; goto errout;
break; break;
} }
@ -2106,7 +2110,7 @@ static int mpls_getroute(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
goto errout; goto errout;
} }
if (!mpls_label_ok(net, in_label, extack)) { if (!mpls_label_ok(net, &in_label, extack)) {
err = -EINVAL; err = -EINVAL;
goto errout; goto errout;
} }