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  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]
Date:   Fri,  8 Jan 2021 16:47:03 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Borislav Petkov <bp@...e.de>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH 02/13] KVM: SVM: Zero out the VMCB array used to track SEV
 ASID association

Zero out the array of VMCB pointers so that pre_sev_run() won't see
garbage when querying the array to detect when an SEV ASID is being
associated with a new VMCB.  In practice, reading random values is all
but guaranteed to be benign as a false negative (which is extremely
unlikely on its own) can only happen on CPU0 on the first VMRUN and would
only cause KVM to skip the ASID flush.  For anything bad to happen, a
previous instance of KVM would have to exit without flushing the ASID,
_and_ KVM would have to not flush the ASID at any time while building the
new SEV guest.

Cc: Borislav Petkov <bp@...e.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Brijesh Singh <brijesh.singh@....com>
Fixes: 70cd94e60c73 ("KVM: SVM: VMRUN should use associated ASID when SEV is enabled")
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 7ef171790d02..ccf52c5531fb 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -573,7 +573,7 @@ static int svm_cpu_init(int cpu)
 	if (svm_sev_enabled()) {
 		sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1,
 					      sizeof(void *),
-					      GFP_KERNEL);
+					      GFP_KERNEL | __GFP_ZERO);
 		if (!sd->sev_vmcbs)
 			goto free_save_area;
 	}
-- 
2.30.0.284.gd98b1dd5eaa7-goog

Powered by blists - more mailing lists