From: Sean Christopherson <seanjc@google.com> stable inclusion from stable-v6.12.95 commit 3b6035bc6bff20e89752ce4358bc4c9a9d5883f2 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16267 CVE: CVE-2026-63940 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 3988bd2723de407ae90fa7a6f6029b4e60238c58 upstream. Explicitly ignore Port I/O requests of length '0' (or count '0'), so that setting up the software scratch area (and other code) doesn't have to worry about underflowing the length, and to allow for WARNing on trying to configure the scratch area with len==0. Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-ID: <20260501202250.2115252-5-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Jack Wang <jinpu.wang@ionos.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zhang Kunbo <zhangkunbo@huawei.com> --- arch/x86/kvm/svm/sev.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 8b6c12d6e48d..6fb67a3b7cbe 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4606,6 +4606,11 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) control->exit_info_1, control->exit_info_2); ret = -EINVAL; break; + case SVM_EXIT_IOIO: + if (!((control->exit_info_1 & SVM_IOIO_SIZE_MASK) >> SVM_IOIO_SIZE_SHIFT)) + return 1; + + fallthrough; default: ret = svm_invoke_exit_handler(vcpu, exit_code); } @@ -4626,6 +4631,9 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in) if (unlikely(check_mul_overflow(count, size, &bytes))) return -EINVAL; + if (!bytes) + return 1; + r = setup_vmgexit_scratch(svm, in, bytes); if (r) return r; -- 2.34.1