linux-kernel - [PATCH V2 5/9] x86/intel_rdt: Fix unchecked MSR access

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1537048707-76280-6-git-send-email-fenghua.yu@intel.com>
Date:   Sat, 15 Sep 2018 14:58:23 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "H Peter Anvin" <hpa@...or.com>,
        "Tony Luck" <tony.luck@...el.com>
Cc:     "Chatre, Reinette" <reinette.chatre@...el.com>,
        "Xiaochen Shen" <xiaochen.shen@...el.com>,
        "Chen Yu" <yu.c.chen@...el.com>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "x86" <x86@...nel.org>, "Fenghua Yu" <fenghua.yu@...el.com>
Subject: [PATCH V2 5/9] x86/intel_rdt: Fix unchecked MSR access

From: Reinette Chatre <reinette.chatre@...el.com>

When a new resource group is created, it is initialized with sane
defaults that currently assume the resource being initialized is a CAT
resource. This code path is also followed by a MBA resource that is not
allocated the same as a CAT resource and as a result we encounter the
following unchecked MSR access error:

unchecked MSR access error: WRMSR to 0xd51 (tried to write 0x0000
000000000064) at rIP: 0xffffffffae059994 (native_write_msr+0x4/0x20)
Call Trace:
mba_wrmsr+0x41/0x80
update_domains+0x125/0x130
rdtgroup_mkdir+0x270/0x500

Fix the above by ensuring the initial allocation is only attempted on a
CAT resource.

Fixes: 95f0b77ef ("x86/intel_rdt: Initialize new resource group with sane defaults")
Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
index ea91750ba27f..74821bc457c0 100644
--- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
+++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c
@@ -2349,6 +2349,12 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 	u32 *ctrl;
 
 	for_each_alloc_enabled_rdt_resource(r) {
+		/*
+		 * Only initialize default allocations for CBM cache
+		 * resources
+		 */
+		if (r->rid == RDT_RESOURCE_MBA)
+			continue;
 		list_for_each_entry(d, &r->domains, list) {
 			d->have_new_ctrl = false;
 			d->new_ctrl = r->cache.shareable_bits;
@@ -2386,6 +2392,12 @@ static int rdtgroup_init_alloc(struct rdtgroup *rdtgrp)
 	}
 
 	for_each_alloc_enabled_rdt_resource(r) {
+		/*
+		 * Only initialize default allocations for CBM cache
+		 * resources
+		 */
+		if (r->rid == RDT_RESOURCE_MBA)
+			continue;
 		ret = update_domains(r, rdtgrp->closid);
 		if (ret < 0) {
 			rdt_last_cmd_puts("failed to initialize allocations\n");
-- 
2.19.0