linux-kernel - [PATCH 0/2] KVM: x86: Enhance vendor module error messages

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: <20211018183929.897461-1-seanjc@google.com>
Date:   Mon, 18 Oct 2021 11:39:27 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
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, Paul Menzel <pmenzel@...gen.mpg.de>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>
Subject: [PATCH 0/2] KVM: x86: Enhance vendor module error messages

Paul Menzel encountered the bad userspace behavior of spamming KVM module
loading on all CPUs, which was mitigated by commit ef935c25fd64 ("kvm: x86:
Limit the number of "kvm: disabled by bios" messages"), except this time
userspace is extra "clever" and spams both kvm_intel and kvm_amd.  Because
the "already loaded the other module" message isn't ratelimited, the bogus
module load managed to spam the kernel log.

Patch 1 addresses another suggestion from Paul by incorporating the vendor
module name into the error messages.

Patch 2 addresses the original report by prioritizing the hardware/bios
support messages over the "already loaded" error.  In additional to
reducing spam, doing so also ensures consistent messaging if a vendor
module isn't supported regardless of what other modules may be loaded.

[*] https://lkml.kernel.org/r/20210818114956.7171-1-pmenzel@molgen.mpg.de

Sean Christopherson (2):
  KVM: x86: Add vendor name to kvm_x86_ops, use it for error messages
  KVM: x86: Defer "already loaded" check until after basic support
    checks

 arch/x86/include/asm/kvm_host.h |  2 ++
 arch/x86/kvm/svm/svm.c          |  2 ++
 arch/x86/kvm/vmx/vmx.c          |  2 ++
 arch/x86/kvm/x86.c              | 17 +++++++++--------
 4 files changed, 15 insertions(+), 8 deletions(-)

-- 
2.33.0.1079.g6e70778dc9-goog