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Wed, 16 Sep 2026 22:32:46 +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 Subject: [PATCH 9/9] s390x/sclp: Reject short headers in PV case Date: Wed, 16 Sep 2026 22:32:41 +0200 Message-ID: <20260916203242.2509787-10-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260916203242.2509787-1-farman@linux.ibm.com> References: <20260916203242.2509787-1-farman@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE2MDI4NSBTYWx0ZWRfX2rl8hdUMBZRe NvenR1tJaHIXCYl4eDYT4SJhdDpejk/e7zQnj2EHpXWemdxvV4AtEergWwfgWT/2TGa8iRdj5e8 hkzmXCChU00otCypHhXGdSGnw/s5nNMkBlwulsNAV+8EXBrhTfH2f7MStGbdJidN6VPculH69hw FXFaRnveQJAplHsxXSMrEgcVe28VuxhJAhqns431lrbz4jzTPjgtW3yYWskR0yP5rgUN+NEza4t 3dTKUqT362ltxT72fABOXXnYZ0yS+r6qIe4SS7wDKnSbR+OL7HD1U9FsOfRtqYmQrUKC6Qt2cZ4 p+eIB9AOUakp0lhPxI33Cpj0yvf7WfUnh4SBHTBYYxDhv8TW8cH2ftuhuN1p7G8m2/Vr55breh+ PKXtmE72LpdG5xqWk8GFzJjOPBcP7yXpEYuFC0tdX7QPF3zkNGAKt7SvGG24S5vLrPbXDGHSIzx mnQ7hP1fmECXNodptkA== X-Authority-Analysis: v=2.4 cv=E/NYNqdl c=1 sm=1 tr=0 ts=6aaafcf3 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=pH6oLB8u_88KfPtTI8IA:9 X-Proofpoint-ORIG-GUID: hKZTJsKM73MynN4ruFk85WBdjFAYQAm3 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE2MDI4NSBTYWx0ZWRfX5Njks9/kL8aG LIfLBVLF69MkSDgTalVe5gzdzEpkMh9Gujo7GzSGibTGOlbmDI2yEIXBMiy0PV8TGCH+sOtC60L I5KanKWb0y3+6JXfFx4yvQkhqBR7/8k= X-Proofpoint-GUID: hKZTJsKM73MynN4ruFk85WBdjFAYQAm3 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=2026-09-16_03,2026-09-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 bulkscore=0 malwarescore=0 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609160285 Received-SPF: pass client-ip=148.163.158.5; envelope-from=farman@linux.ibm.com; helo=mx0b-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_H3=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 Fixes: c1db53a591 ("s390/sclp: read sccb from mem based on provided lengt= h") 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