linux-kernel - [PATCH] svm: Add mutex_lock to protect apic_access_page

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-next>] [day] [month] [year] [list]

Message-ID: <20181112122255.128953-1-Suravee.Suthikulpanit@amd.com>
Date:   Mon, 12 Nov 2018 12:23:14 +0000
From:   "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
CC:     "joro@...tes.org" <joro@...tes.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        Wei Wang <wawei@...zon.de>,
        Amadeusz Juskowiak <ajusk@...zon.de>,
        Julian Stecklina <jsteckli@...zon.de>,
        "Suthikulpanit, Suravee" <Suravee.Suthikulpanit@....com>
Subject: [PATCH] svm: Add mutex_lock to protect apic_access_page_done on AMD
 systems

From: Wei Wang <wawei@...zon.de>

There is a race condition when accessing kvm->arch.apic_access_page_done.
Due to it, x86_set_memory_region will fail when creating the second vcpu
for a svm guest.

Add a mutex_lock to serialize the accesses to apic_access_page_done.
This lock is also used by vmx for the same purpose.

Signed-off-by: Wei Wang <wawei@...zon.de>
Signed-off-by: Amadeusz Juskowiak <ajusk@...zon.de>
Signed-off-by: Julian Stecklina <jsteckli@...zon.de>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
---
 arch/x86/kvm/svm.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d96092b35936..8be1718fed1d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1658,20 +1658,23 @@ static u64 *avic_get_physical_id_entry(struct kvm_vcpu *vcpu,
 static int avic_init_access_page(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
-	int ret;
+	int ret = 0;
 
+	mutex_lock(&kvm->slots_lock);
 	if (kvm->arch.apic_access_page_done)
-		return 0;
+		goto out;
 
-	ret = x86_set_memory_region(kvm,
-				    APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
-				    APIC_DEFAULT_PHYS_BASE,
-				    PAGE_SIZE);
+	ret = __x86_set_memory_region(kvm,
+				      APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
+				      APIC_DEFAULT_PHYS_BASE,
+				      PAGE_SIZE);
 	if (ret)
-		return ret;
+		goto out;
 
 	kvm->arch.apic_access_page_done = true;
-	return 0;
+out:
+	mutex_unlock(&kvm->slots_lock);
+	return ret;
 }
 
 static int avic_init_backing_page(struct kvm_vcpu *vcpu)
-- 
2.17.1