From e7f17d033e58acce9df40bc44ed804720417ca2e Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 8 Mar 2018 18:39:24 +0000 Subject: mpls, nospec: Sanitize array index in mpls_label_ok() 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: "David S. Miller" Cc: Eric W. Biederman Signed-off-by: Dan Williams Signed-off-by: David S. Miller [bwh: Backported to 4.4: - mpls_label_ok() doesn't take an extack parameter - Drop change in mpls_getroute()] Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- net/mpls/af_mpls.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index ff7f7f05523a..c2ce7dec5198 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -714,17 +715,20 @@ 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) { + bool is_ok = true; + /* Reserved labels may not be set */ - if (index < MPLS_LABEL_FIRST_UNRESERVED) - return false; + if (*index < MPLS_LABEL_FIRST_UNRESERVED) + is_ok = false; /* The full 20 bit range may not be supported. */ - if (index >= net->mpls.platform_labels) - return false; + if (is_ok && *index >= net->mpls.platform_labels) + 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) @@ -745,7 +749,7 @@ static int mpls_route_add(struct mpls_route_config *cfg) index = find_free_label(net); } - if (!mpls_label_ok(net, index)) + if (!mpls_label_ok(net, &index)) goto errout; /* Append makes no sense with mpls */ @@ -806,7 +810,7 @@ static int mpls_route_del(struct mpls_route_config *cfg) index = cfg->rc_label; - if (!mpls_label_ok(net, index)) + if (!mpls_label_ok(net, &index)) goto errout; mpls_route_update(net, index, NULL, &cfg->rc_nlinfo); @@ -1166,7 +1170,7 @@ static int rtm_to_route_config(struct sk_buff *skb, struct nlmsghdr *nlh, goto errout; if (!mpls_label_ok(cfg->rc_nlinfo.nl_net, - cfg->rc_label)) + &cfg->rc_label)) goto errout; break; } -- cgit v1.2.3