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Tue, 11 Aug 2026 15:56:44 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 11 Aug 2026 15:56:44 +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 v1 10/11] KVM: s390: Fix potential tiny kernel stack leak Date: Tue, 11 Aug 2026 17:56:40 +0200 Message-ID: <20260811155641.219777-11-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260811155641.219777-1-imbrenda@linux.ibm.com> References: <20260811155641.219777-1-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=RsP16imK c=1 sm=1 tr=0 ts=6a7b4643 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=geH3wxNwSTHpAUJZdnsA:9 X-Proofpoint-GUID: VDJcknpbUZpTH6TGfOW1U-NtjTSzXV8S X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODExMDEzMCBTYWx0ZWRfX1GeHrmgpHjxV jvxc6OrysekDvyf8qx4lvy2FCz0Wn2w+hjINZCTxPGpGJAtuBztGC9H/zEYIs6OiDiulk4iE+dU ThHZQuTDuKuqQ24ZG+4IsUYtnOXEJuq1VdS+ZGLN30qezQr//A/s0hbvC3GiMGA2SsTk129vKeW hZZTmEe1J3gV/kyKoFRowpsvU65PZMamWG3Tg771ig4D1KeGhZcTDt+p/0IUOHTzxBDGwJxmzXh B+pBrvpLi/yZoGrRE5ppgoTdU9tXye+mTv88dAqgKfbmTG4ffSaQpJGumUPLTdtjmToQEx0tWvJ aYdNGlu6aw+IGLBt1ZW8PC438hEz8hRAeclxwXuazO0sCTIn+A5TILVHCiZIxf9RbeGOx2XeUhz eywMAbJ6NNGFon0q7r7X6wHWaqt8YBuDpooL9v8DcXvHi2X98gjubplCctDfCSXQ5Zce2kePvFA 1taO9ZVb+zbkLHt9baw== X-Proofpoint-ORIG-GUID: VDJcknpbUZpTH6TGfOW1U-NtjTSzXV8S X-Proofpoint-Spam-Info: AW1haW4tMjYwODExMDEzMCBTYWx0ZWRfX5n+u6bRyk4nk KitJ55FEenjIVUgjlvJx/wDHy0e1Nlv+CvQzLKLnJfAlyPjmCtHziLMFNXM4ViTfa/Jx4xglE+G hbOAO3QVJAIGutQnGAGylkpPkRObfv4= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-11_03,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 suspectscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608110130 In some circumstances, one bit of kernel stack could have been leaked from dat_cond_set_storage_key(). Fix by clearing prev before use. Fixes: 8e03e8316eb2 ("KVM: s390: KVM page table management functions: storage keys") Signed-off-by: Claudio Imbrenda --- arch/s390/kvm/dat.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c index 47ff8af1b22f..e2a74eb4d631 100644 --- a/arch/s390/kvm/dat.c +++ b/arch/s390/kvm/dat.c @@ -740,6 +740,7 @@ int dat_cond_set_storage_key(struct kvm_s390_mmu_cache *mmc, union asce asce, gf pgste.fp = skey.fp; pgste.gc = skey.c; pgste.gr = skey.r; + prev.skey = 0; if (!ptep->h.i) { rc = page_cond_set_storage_key(pte_origin(*ptep), skey, &prev, nq, mr, mc); -- 2.55.0