From c7563e62a6d720aa3b068e26ddffab5f0df29263 Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Mon, 10 Jun 2019 13:15:44 -0400 Subject: x86/resctrl: Prevent NULL pointer dereference when local MBM is disabled Booting with kernel parameter "rdt=cmt,mbmtotal,memlocal,l3cat,mba" and executing "mount -t resctrl resctrl -o mba_MBps /sys/fs/resctrl" results in a NULL pointer dereference on systems which do not have local MBM support enabled.. BUG: kernel NULL pointer dereference, address: 0000000000000020 PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 722 Comm: kworker/0:3 Not tainted 5.2.0-0.rc3.git0.1.el7_UNSUPPORTED.x86_64 #2 Workqueue: events mbm_handle_overflow RIP: 0010:mbm_handle_overflow+0x150/0x2b0 Only enter the bandwith update loop if the system has local MBM enabled. Fixes: de73f38f7680 ("x86/intel_rdt/mba_sc: Feedback loop to dynamically update mem bandwidth") Signed-off-by: Prarit Bhargava Signed-off-by: Thomas Gleixner Cc: Fenghua Yu Cc: Reinette Chatre Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190610171544.13474-1-prarit@redhat.com --- arch/x86/kernel/cpu/resctrl/monitor.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch') diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 1573a0a6b525..ff6e8e561405 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -368,6 +368,9 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_domain *dom_mbm) struct list_head *head; struct rdtgroup *entry; + if (!is_mbm_local_enabled()) + return; + r_mba = &rdt_resources_all[RDT_RESOURCE_MBA]; closid = rgrp->closid; rmid = rgrp->mon.rmid; -- cgit v1.2.3-59-g8ed1b