This is a note to let you know that I've just added the patch titled
mpls, nospec: Sanitize array index in mpls_label_ok()
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: mpls-nospec-sanitize-array-index-in-mpls_label_ok.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From ben.hutchings@codethink.co.uk Thu Mar 8 17:18:02 2018
From: Ben Hutchings ben.hutchings@codethink.co.uk Date: Thu, 8 Mar 2018 18:39:24 +0000 Subject: mpls, nospec: Sanitize array index in mpls_label_ok() To: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Dan Williams dan.j.williams@intel.com, "David S. Miller" davem@davemloft.net, "Eric W. Biederman" ebiederm@xmission.com, stable@vger.kernel.org Message-ID: 20180308183924.wvu2reoicwgmzerx@xylophone.i.decadent.org.uk Content-Disposition: inline
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: "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 [bwh: Backported to 4.4: - mpls_label_ok() doesn't take an extack parameter - Drop change in mpls_getroute()] Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mpls/af_mpls.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
--- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -7,6 +7,7 @@ #include <linux/if_arp.h> #include <linux/ipv6.h> #include <linux/mpls.h> +#include <linux/nospec.h> #include <linux/vmalloc.h> #include <net/ip.h> #include <net/dst.h> @@ -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_ro 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_ro
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 goto errout;
if (!mpls_label_ok(cfg->rc_nlinfo.nl_net, - cfg->rc_label)) + &cfg->rc_label)) goto errout; break; }
Patches currently in stable-queue which might be from ben.hutchings@codethink.co.uk are
queue-4.4/x86-spectre-fix-an-error-message.patch queue-4.4/revert-led-core-fix-brightness-setting-when-setting-delay_off-0.patch queue-4.4/net-mpls-pull-common-label-check-into-helper.patch queue-4.4/x86-apic-vector-handle-legacy-irq-data-correctly.patch queue-4.4/mpls-nospec-sanitize-array-index-in-mpls_label_ok.patch