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Mon, 21 Sep 2026 20:43:09 +0200 (CEST) From: Eric Farman To: Christian Borntraeger , Matthew Rosato Cc: Cornelia Huck , qemu-s390x@nongnu.org, qemu-devel@nongnu.org, Eric Farman , Janosch Frank , qemu-stable@nongnu.org Subject: [PATCH v2 9/9] s390x/sclp: Reject short headers in PV case Date: Mon, 21 Sep 2026 20:43:05 +0200 Message-ID: <20260921184305.3791311-10-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260921184305.3791311-1-farman@linux.ibm.com> References: <20260921184305.3791311-1-farman@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ttWEbJkaDqaXvVGQDPtSVB1uHL1n6nE9 X-Authority-Analysis: v=2.4 cv=EOCTQFZC c=1 sm=1 tr=0 ts=6ab17ac2 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=69wJf7TsAAAA:8 a=pH6oLB8u_88KfPtTI8IA:9 a=Fg1AiH1G6rFz08G2ETeA:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIxMDI3MiBTYWx0ZWRfX+CFTVMOAugtF lb2vbbePPfBKQLpJ2nWdc7RysKQ2RWYxXFk82XfTld3zVsNhs6LsErW4dfvRNHJRwFx7GHkXwnb gcPyrfax6P2jWqHLopQkj9qgAn4FFik= X-Proofpoint-GUID: ttWEbJkaDqaXvVGQDPtSVB1uHL1n6nE9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIxMDI3MiBTYWx0ZWRfX+OYaILPyoVJu AE9Oy2r8KHRMiMlJckPoevlY4rCubavryQlWQ8BSY4mrYvFzWh4YLGBSVDpVvpShCBL4rB++XRR RmkmKJrSsZ2Esfc2kN84cMoQ124nspp/iNn0Dp2gxjF4QmvheSnvAwpcDd3Sy4CLMPWBQJC9+nW u3JS1RYff6/dVVRpMYCX5KlHqkZI74jHh7oz62Bw7BXP1mEfUWx7gldwhGQBk1cAGiOUjdiVO4y 0VxDfHCh/h3a3a/tOBctNISDXNQ/g/qzJ+Y6qci8Zzjn0504l7gw9hOxhgktzmuKX2jySDWTRxY DrcaKIvpd75GPZRqecS4LejWKxmx5voh/xNlJljULjNYm02Re+7lzuEhMQuRGNpR6afLo/W3PaF oOSi3DCsc9ls0qA5lV40xPdx1mhInLF2jCs2jH/sxeWQaJ1OF5qG9OB19ei9/Bxt0a2NQCNRuLv NCQG+AlQ2DuxL6nOJ8Q== 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=2026-09-21_05,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 priorityscore=1501 clxscore=1015 spamscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609210272 Received-SPF: pass client-ip=148.163.156.1; envelope-from=farman@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org An invalid length in an SCCB header correctly generates a specification exception for the regular (non-PV) codepath that processes an SCLP instruction intercept. The PV case doesn't, even though such a thing should already be sanitized. Since a short length will cause problems later down the line with the storage that will be allocated based on that size, put up a defensive check and return if it is too short. Cc: Janosch Frank Cc: qemu-stable@nongnu.org Fixes: c1db53a591 ("s390/sclp: read sccb from mem based on provided lengt= h") Reviewed-by: Matthew Rosato Acked-by: Christian Borntraeger Signed-off-by: Eric Farman --- hw/s390x/sclp.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c index d8b655efcc..ad8129a5d8 100644 --- a/hw/s390x/sclp.c +++ b/hw/s390x/sclp.c @@ -277,6 +277,11 @@ int sclp_service_call_protected(S390CPU *cpu, uint64= _t sccb, uint32_t code) =20 s390_cpu_pv_mem_read(env_archcpu(env), 0, &header, sizeof(SCCBHeader= )); =20 + /* Do nothing if the header appears malformed */ + if (be16_to_cpu(header.length) < sizeof(SCCBHeader)) { + goto out_no_write; + } + work_sccb =3D g_malloc0(be16_to_cpu(header.length)); s390_cpu_pv_mem_read(env_archcpu(env), 0, work_sccb, be16_to_cpu(header.length)); @@ -290,6 +295,7 @@ int sclp_service_call_protected(S390CPU *cpu, uint64_= t sccb, uint32_t code) out_write: s390_cpu_pv_mem_write(env_archcpu(env), 0, work_sccb, be16_to_cpu(header.length)); +out_no_write: sclp_c->service_interrupt(sclp, SCLP_PV_DUMMY_ADDR); return 0; } --=20 2.53.0