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Fri, 11 Sep 2020 14:50:19 +0000 (GMT) Subject: Re: [PATCH v5 2/8] s390/sclp: rework sclp boundary checks To: Cornelia Huck , Thomas Huth References: <20200910093655.255774-1-walling@linux.ibm.com> <20200910093655.255774-3-walling@linux.ibm.com> <4c495858-c7aa-2e12-ef2b-26952019e8ef@redhat.com> <20200911122424.582340f4.cohuck@redhat.com> From: Collin Walling Message-ID: Date: Fri, 11 Sep 2020 10:50:19 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200911122424.582340f4.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-09-11_05:2020-09-10, 2020-09-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 impostorscore=0 bulkscore=0 priorityscore=1501 adultscore=0 mlxlogscore=999 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009110114 Received-SPF: pass client-ip=148.163.158.5; envelope-from=walling@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/11 09:50:13 X-ACL-Warn: Detected OS = Linux 3.x [generic] X-Spam_score_int: -51 X-Spam_score: -5.2 X-Spam_bar: ----- X-Spam_report: (-5.2 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-2.469, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: frankja@linux.ibm.com, david@redhat.com, mst@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, pbonzini@redhat.com, sumanthk@linux.ibm.com, mihajlov@linux.ibm.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/11/20 6:24 AM, Cornelia Huck wrote: > On Thu, 10 Sep 2020 19:45:01 +0200 > Thomas Huth wrote: > >> On 10/09/2020 11.36, Collin Walling wrote: >>> Rework the SCLP boundary check to account for different SCLP commands >>> (eventually) allowing different boundary sizes. >>> >>> Signed-off-by: Collin Walling >>> Acked-by: Janosch Frank >>> Reviewed-by: Cornelia Huck >>> --- >>> hw/s390x/sclp.c | 19 ++++++++++++++++++- >>> 1 file changed, 18 insertions(+), 1 deletion(-) >>> >>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c >>> index 28b973de8f..69a8724dc7 100644 >>> --- a/hw/s390x/sclp.c >>> +++ b/hw/s390x/sclp.c >>> @@ -49,6 +49,18 @@ static inline bool sclp_command_code_valid(uint32_t code) >>> return false; >>> } >>> >>> +static bool sccb_verify_boundary(uint64_t sccb_addr, uint16_t len) >> >> Maybe it would be good to add a comment in front of the function to say >> that len must be big endian? > > What about renaming it to sccb_h_len or so? That would make it more > clear that the parameter is not just some random length. > I think that makes sense. >> >> Thomas >> >>> +{ >>> + uint64_t sccb_max_addr = sccb_addr + be16_to_cpu(len) - 1; >>> + uint64_t sccb_boundary = (sccb_addr & PAGE_MASK) + PAGE_SIZE; >>> + >>> + if (sccb_max_addr < sccb_boundary) { >>> + return true; >>> + } >>> + >>> + return false; >>> +} >>> + >>> static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int *count) >>> { >>> uint8_t features[SCCB_CPU_FEATURE_LEN] = { 0 }; >>> @@ -229,6 +241,11 @@ int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb, >>> goto out_write; >>> } >>> >>> + if (!sccb_verify_boundary(sccb, work_sccb.h.length)) { > > ...name inspired by the 'h' in here. > >>> + work_sccb.h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION); >>> + goto out_write; >>> + } >>> + >>> sclp_c->execute(sclp, &work_sccb, code); >>> out_write: >>> s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb, >>> @@ -274,7 +291,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code) >>> goto out_write; >>> } >>> >>> - if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) + PAGE_SIZE)) { >>> + if (!sccb_verify_boundary(sccb, work_sccb.h.length)) { >>> work_sccb.h.response_code = cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION); >>> goto out_write; >>> } >>> >> > > -- Regards, Collin Stay safe and stay healthy