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Wed, 12 Aug 2026 10:44:38 +0000 (GMT) Received: from p-imbrenda.ehn-de.ibm.com (unknown [9.224.75.30]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Aug 2026 10:44:38 +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 v2 8/9] KVM: s390: Fix potential tiny kernel stack leak Date: Wed, 12 Aug 2026 12:44:35 +0200 Message-ID: <20260812104436.109741-9-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260812104436.109741-1-imbrenda@linux.ibm.com> References: <20260812104436.109741-1-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-Authority-Analysis: v=2.4 cv=AMtp2X5w c=1 sm=1 tr=0 ts=6a7c4e9c cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=geH3wxNwSTHpAUJZdnsA:9 X-Proofpoint-GUID: zKtHnT7cuHxN1Cfbn7xW3zQiN1SdrAyn X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEyMDA4NCBTYWx0ZWRfX+J6W8J4JGWcA qg14DnlIzCmCyk6zMaX7F90n7lqwRrDq5jlbCQ+p+O4sRb0EP8hGLe69w4POFWi23wSoqo5B8x7 VGaqP7cbSYYbbLke+sgeJ5vvWj5rtu8hauYUhFI72CSmXW3z9oDrmZM7n+Z0LaSVqPmjylE5ekY yzskKDhu+yz5ybG+/afFdMZeeN/kK/Tnx2ck0whiENNWL7WyRaYhdd7VYzUg7qDS0kfV9UhBCYL 2e3TCUJHj81Bqik0paX0701x60RZ2ELIhxh/7/a727J+W2Cm7ylAKf+Hbo36s1sLnDJSluonSg7 fHEH2YnHzO7f9FO8SPPnnUxVyw4nP6vOhvOUawI8hzxeb8+wh/MzFAmlYpoVmKBLexX3ktxycA5 NcYang1rz0Mzh7sPMN8WGfxT8yH1sIMf6HzFwjxtm4Ui/kvKz2alFW5IWWcsIKrODUWgFrlpx3E e6YwZ53KX3LQmirZoRA== X-Proofpoint-ORIG-GUID: zKtHnT7cuHxN1Cfbn7xW3zQiN1SdrAyn X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDA4NCBTYWx0ZWRfX/jEABY1L4PMo hEn5hRKwXyfxBkPMw9w4aHSRvFTtQItTW7ZCUHvP7ZxVhqRAX6pwQmEoZCZ1b0ahJ0svFcuU0vt Yak+W+rr8k2jCCnFYo82VvwKR72CEYQ= 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=2026-08-12_03,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 lowpriorityscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 phishscore=0 spamscore=0 bulkscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608120084 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 Reviewed-by: Christian Borntraeger --- 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 f4dd6f783417..f2ea013cb33e 100644 --- a/arch/s390/kvm/dat.c +++ b/arch/s390/kvm/dat.c @@ -737,6 +737,7 @@ 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