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Mon, 27 Jul 2026 15:03:05 +0000 (GMT) Received: from p-imbrenda.ibmuc.com (unknown [9.111.1.146]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 27 Jul 2026 15:03:05 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: [PATCH v3 10/10] KVM: s390: Fix cleanup in kvm_s390_pv_create_cpu() Date: Mon, 27 Jul 2026 17:02:54 +0200 Message-ID: <20260727150254.236021-11-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260727150254.236021-1-imbrenda@linux.ibm.com> References: <20260727150254.236021-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PFfbjfR52AjBG9fIJt8OTJ_dg0Cv--UX X-Proofpoint-ORIG-GUID: PFfbjfR52AjBG9fIJt8OTJ_dg0Cv--UX X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI3MDE0MCBTYWx0ZWRfXz34kMiiU93r/ H0EPDRNYPNudeNq43+YTNdEdtCECUJEcB5r6VhdwnKavIloXyh8qIggm8Hjwxp8fm/H9VeJUcY6 1eAF53cTHHCPkox/oTBoU/cvhpbBSb0eIjHcZ0L7gCnfURaLCG2q4swGYBM+JrcLsYhCGpa6/6h gqgxadrnTFsiq1V/bP8k5ONQ9p2InqZDB8NVn+XmLMgMi1hPFdys8j2qbSCEp8fcj6r69ZI59Og 8/85mKhi+75myx3nS3XEEje8Hsk5CWHiMvG4AruZhggLpjLL2J5TPyNY/QJSvHXRwYyteV+WMS4 icEG3YQBtbqeyVJUT5fKLBdUMguQ6b7rPRk76Ldapa1M6eT2LmfMHi8z1rL0+dmJp4Nsg4jl/hQ esRkTUeKbvcvWD145KVI1QM+YAneztGM2+5N6eaVwNy5lz/fP7Sv8y4Zzrfo2hbMSaFwB+HtNLM K1HLs4qXxdn4ZWRQUow== X-Authority-Analysis: v=2.4 cv=SKFykuvH c=1 sm=1 tr=0 ts=6a677330 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=h-RzbZz0cncsEQf3j_AA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI3MDE0MCBTYWx0ZWRfX2tZWgIWAOYJw uw12etFXONbkE3afsamwaFqZ52xFaj1gzS8ZK7g6fhwJZQcfafvv2C0peoBbWyTaKFjmzmTi8kN VzFqsC3LVU1ozQd4tP5rac4h9GUOPfE= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-27_04,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 phishscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607270140 If creating a protected vCPU in kvm_s390_pv_create_cpu() fails, kvm_s390_pv_destroy_cpu() was called, which checks whether the vCPU has a PV handle and exits doing nothing otherwise. At that point, due to not having created the protected vCPU, the PV handle will not be set, and kvm_s390_pv_destroy_cpu() will do nothing, thus leaking the allocated memory. Fix by factoring out the code to free and reset a PV vCPU; call it from kvm_s390_pv_destroy_cpu() and kvm_s390_pv_create_cpu(). Fixes: d4074324b07a ("KVM: s390: pv: avoid double free of sida page") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/pv.c | 41 +++++++++++++++++++++-------------------- 1 file changed, 21 insertions(+), 20 deletions(-) diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c index dc204b521052..b02e0159d3cd 100644 --- a/arch/s390/kvm/pv.c +++ b/arch/s390/kvm/pv.c @@ -244,6 +244,24 @@ static void kvm_s390_clear_pv_state(struct kvm *kvm) kvm->arch.pv.stor_var = NULL; } +static void kvm_s390_pv_dispose_cpu(struct kvm_vcpu *vcpu, bool free_stor_base) +{ + if (free_stor_base) + free_pages(vcpu->arch.pv.stor_base, get_order(uv_info.guest_cpu_stor_len)); + free_page((unsigned long)sida_addr(vcpu->arch.sie_block)); + vcpu->arch.sie_block->pv_handle_cpu = 0; + vcpu->arch.sie_block->pv_handle_config = 0; + memset(&vcpu->arch.pv, 0, sizeof(vcpu->arch.pv)); + vcpu->arch.sie_block->sdf = 0; + /* + * The sidad field (for sdf == 2) is now the gbea field (for sdf == 0). + * Use the reset value of gbea to avoid leaking the kernel pointer of + * the just freed sida. + */ + vcpu->arch.sie_block->gbea = 1; + kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); +} + int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) { int cc; @@ -258,24 +276,9 @@ int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) WARN_ONCE(cc, "protvirt destroy cpu failed rc %x rrc %x", *rc, *rrc); /* Intended memory leak for something that should never happen. */ - if (!cc) - free_pages(vcpu->arch.pv.stor_base, - get_order(uv_info.guest_cpu_stor_len)); - - free_page((unsigned long)sida_addr(vcpu->arch.sie_block)); - vcpu->arch.sie_block->pv_handle_cpu = 0; - vcpu->arch.sie_block->pv_handle_config = 0; - memset(&vcpu->arch.pv, 0, sizeof(vcpu->arch.pv)); - vcpu->arch.sie_block->sdf = 0; - /* - * The sidad field (for sdf == 2) is now the gbea field (for sdf == 0). - * Use the reset value of gbea to avoid leaking the kernel pointer of - * the just freed sida. - */ - vcpu->arch.sie_block->gbea = 1; - kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); + kvm_s390_pv_dispose_cpu(vcpu, !cc); - return cc ? EIO : 0; + return cc ? -EIO : 0; } int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) @@ -319,9 +322,7 @@ int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc) uvcb.header.rrc); if (cc) { - u16 dummy; - - kvm_s390_pv_destroy_cpu(vcpu, &dummy, &dummy); + kvm_s390_pv_dispose_cpu(vcpu, true); return -EIO; } -- 2.55.0