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Fri, 11 Sep 2020 10:24:26 +0000 (UTC) Date: Fri, 11 Sep 2020 12:24:24 +0200 From: Cornelia Huck To: Thomas Huth Subject: Re: [PATCH v5 2/8] s390/sclp: rework sclp boundary checks Message-ID: <20200911122424.582340f4.cohuck@redhat.com> In-Reply-To: <4c495858-c7aa-2e12-ef2b-26952019e8ef@redhat.com> References: <20200910093655.255774-1-walling@linux.ibm.com> <20200910093655.255774-3-walling@linux.ibm.com> <4c495858-c7aa-2e12-ef2b-26952019e8ef@redhat.com> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=cohuck@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/11 03:28:41 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: Collin Walling , frankja@linux.ibm.com, mst@redhat.com, david@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 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. > > 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; > > } > > >