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Mon, 25 May 2020 10:53:58 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 34C5511C04A; Mon, 25 May 2020 10:53:58 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8248D11C04C; Mon, 25 May 2020 10:53:57 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.30.189]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 25 May 2020 10:53:57 +0000 (GMT) Subject: Re: [PATCH v2 3/8] s390/sclp: rework sclp boundary and length checks To: Cornelia Huck , Collin Walling References: <20200515222032.18838-1-walling@linux.ibm.com> <20200515222032.18838-4-walling@linux.ibm.com> <2fcd0d94-12c7-e3b8-d6a6-3c512ae25150@linux.ibm.com> <20200519151936.1071fa14.cohuck@redhat.com> From: Janosch Frank Autocrypt: addr=frankja@linux.ibm.com; prefer-encrypt=mutual; keydata= mQINBFubpD4BEADX0uhkRhkj2AVn7kI4IuPY3A8xKat0ihuPDXbynUC77mNox7yvK3X5QBO6 qLqYr+qrG3buymJJRD9xkp4mqgasHdB5WR9MhXWKH08EvtvAMkEJLnqxgbqf8td3pCQ2cEpv 15mH49iKSmlTcJ+PvJpGZcq/jE42u9/0YFHhozm8GfQdb9SOI/wBSsOqcXcLTUeAvbdqSBZe zuMRBivJQQI1esD9HuADmxdE7c4AeMlap9MvxvUtWk4ZJ/1Z3swMVCGzZb2Xg/9jZpLsyQzb lDbbTlEeyBACeED7DYLZI3d0SFKeJZ1SUyMmSOcr9zeSh4S4h4w8xgDDGmeDVygBQZa1HaoL Esb8Y4avOYIgYDhgkCh0nol7XQ5i/yKLtnNThubAcxNyryw1xSstnKlxPRoxtqTsxMAiSekk 0m3WJwvwd1s878HrQNK0orWd8BzzlSswzjNfQYLF466JOjHPWFOok9pzRs+ucrs6MUwDJj0S cITWU9Rxb04XyigY4XmZ8dywaxwi2ZVTEg+MD+sPmRrTw+5F+sU83cUstuymF3w1GmyofgsU Z+/ldjToHnq21MNa1wx0lCEipCCyE/8K9B9bg9pUwy5lfx7yORP3JuAUfCYb8DVSHWBPHKNj HTOLb2g2UT65AjZEQE95U2AY9iYm5usMqaWD39pAHfhC09/7NQARAQABtCVKYW5vc2NoIEZy YW5rIDxmcmFua2phQGxpbnV4LmlibS5jb20+iQI3BBMBCAAhBQJbm6Q+AhsjBQsJCAcCBhUI CQoLAgQWAgMBAh4BAheAAAoJEONU5rjiOLn4p9gQALjkdj5euJVI2nNT3/IAxAhQSmRhPEt0 AmnCYnuTcHRWPujNr5kqgtyER9+EMQ0ZkX44JU2q7OWxTdSNSAN/5Z7qmOR9JySvDOf4d3mS bMB5zxL9d8SbnSs1uW96H9ZBTlTQnmLfsiM9TetAjSrR8nUmjGhe2YUhJLR1v1LguME+YseT eXnLzIzqqpu311/eYiiIGcmaOjPCE+vFjcXL5oLnGUE73qSYiujwhfPCCUK0850o1fUAYq5p CNBCoKT4OddZR+0itKc/cT6NwEDwdokeg0+rAhxb4Rv5oFO70lziBplEjOxu3dqgIKbHbjza EXTb+mr7VI9O4tTdqrwJo2q9zLqqOfDBi7NDvZFLzaCewhbdEpDYVu6/WxprAY94hY3F4trT rQMHJKQENtF6ZTQc9fcT5I3gAmP+OEvDE5hcTALpWm6Z6SzxO7gEYCnF+qGXqp8sJVrweMub UscyLqHoqdZC2UG4LQ1OJ97nzDpIRe0g6oJ9ZIYHKmfw5jjwH6rASTld5MFWajWdNsqK15k/ RZnHAGICKVIBOBsq26m4EsBlfCdt3b/6emuBjUXR1pyjHMz2awWzCq6/6OWs5eANZ0sdosNq dq2v0ULYTazJz2rlCXV89qRa7ukkNwdBSZNEwsD4eEMicj1LSrqWDZMAALw50L4jxaMD7lPL jJbauQINBFubpD4BEADAcUTRqXF/aY53OSH7IwIK9lFKxIm0IoFkOEh7LMfp7FGzaP7ANrZd cIzhZi38xyOkcaFY+npGEWvko7rlIAn0JpBO4x3hfhmhBD/WSY8LQIFQNNjEm3vzrMo7b9Jb JAqQxfbURY3Dql3GUzeWTG9uaJ00u+EEPlY8zcVShDltIl5PLih20e8xgTnNzx5c110lQSu0 iZv2lAE6DM+2bJQTsMSYiwKlwTuv9LI9Chnoo6+tsN55NqyMxYqJgElk3VzlTXSr3+rtSCwf tq2cinETbzxc1XuhIX6pu/aCGnNfuEkM34b7G1D6CPzDMqokNFbyoO6DQ1+fW6c5gctXg/lZ 602iEl4C4rgcr3+EpfoPUWzKeM8JXv5Kpq4YDxhvbitr8Dm8gr38+UKFZKlWLlwhQ56r/zAU v6LIsm11GmFs2/cmgD1bqBTNHHcTWwWtRTLgmnqJbVisMJuYJt4KNPqphTWsPY8SEtbufIlY HXOJ2lqUzOReTrie2u0qcSvGAbSfec9apTFl2Xko/ddqPcZMpKhBiXmY8tJzSPk3+G4tqur4 6TYAm5ouitJsgAR61Cu7s+PNuq/pTLDhK+6/Njmc94NGBcRA4qTuysEGE79vYWP2oIAU4Fv6 gqaWHZ4MEI2XTqH8wiwzPdCQPYsSE0fXWiYu7ObeErT6iLSTZGx4rQARAQABiQIfBBgBCAAJ BQJbm6Q+AhsMAAoJEONU5rjiOLn4DDEP/RuyckW65SZcPG4cMfNgWxZF8rVjeVl/9PBfy01K 8R0hajU40bWtXSMiby7j0/dMjz99jN6L+AJHJvrLz4qYRzn2Ys843W+RfXj62Zde4YNBE5SL jJweRCbMWKaJLj6499fctxTyeb9+AMLQS4yRSwHuAZLmAb5AyCW1gBcTWZb8ON5BmWnRqeGm IgC1EvCnHy++aBnHTn0m+zV89BhTLTUal35tcjUFwluBY39R2ux/HNlBO1GY3Z+WYXhBvq7q katThLjaQSmnOrMhzqYmdShP1leFTVbzXUUIYv/GbynO/YrL2gaQpaP1bEUEi8lUAfXJbEWG dnHFkciryi092E8/9j89DJg4mmZqOau7TtUxjRMlBcIliXkzSLUk+QvD4LK1kWievJse4mte FBdkWHfP4BH/+8DxapRcG1UAheSnSRQ5LiO50annOB7oXF+vgKIaie2TBfZxQNGAs3RQ+bga DchCqFm5adiSP5+OT4NjkKUeGpBe/aRyQSle/RropTgCi85pje/juYEn2P9UAgkfBJrOHvQ9 Z+2Sva8FRd61NJLkCJ4LFumRn9wQlX2icFbi8UDV3do0hXJRRYTWCxrHscMhkrFWLhYiPF4i phX7UNdOWBQ90qpHyAxHmDazdo27gEjfvsgYMdveKknEOTEb5phwxWgg7BcIDoJf9UMC Message-ID: Date: Mon, 25 May 2020 12:53:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200519151936.1071fa14.cohuck@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="eRln5ziRD2q6Rn1DegXOXUkRvoqM4u0Vr" X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.676 definitions=2020-05-25_05:2020-05-25, 2020-05-25 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 impostorscore=0 cotscore=-2147483648 spamscore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 mlxlogscore=999 mlxscore=0 clxscore=1015 malwarescore=0 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2005250082 Received-SPF: pass client-ip=148.163.156.1; envelope-from=frankja@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/25 06:50:15 X-ACL-Warn: Detected OS = Linux 3.1-3.10 [fuzzy] X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, KHOP_DYNAMIC=0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: thuth@redhat.com, mst@redhat.com, david@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, svens@linux.ibm.com, pbonzini@redhat.com, mihajlov@linux.ibm.com, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --eRln5ziRD2q6Rn1DegXOXUkRvoqM4u0Vr Content-Type: multipart/mixed; boundary="e5s5OZqfvRUhatcbhJPVtjYtw4xlFloM4" --e5s5OZqfvRUhatcbhJPVtjYtw4xlFloM4 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 5/19/20 3:19 PM, Cornelia Huck wrote: > On Mon, 18 May 2020 11:15:07 -0400 > Collin Walling wrote: >=20 >> On 5/18/20 4:50 AM, Janosch Frank wrote: >>> On 5/16/20 12:20 AM, Collin Walling wrote: =20 >>>> Rework the SCLP boundary check to account for different SCLP command= s >>>> (eventually) allowing different boundary sizes. >>>> >>>> Move the length check code into a separate function, and introduce a= >>>> new function to determine the length of the read SCP data (i.e. the = size >>>> from the start of the struct to where the CPU entries should begin).= >>>> >>>> Signed-off-by: Collin Walling >>>> --- >>>> hw/s390x/sclp.c | 57 ++++++++++++++++++++++++++++++++++++++++++----= --- >>>> 1 file changed, 49 insertions(+), 8 deletions(-) >>>> >>>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c >>>> index 2bd618515e..987699e3c4 100644 >>>> --- a/hw/s390x/sclp.c >>>> +++ b/hw/s390x/sclp.c >>>> @@ -49,6 +49,34 @@ static inline bool sclp_command_code_valid(uint32= _t code) >>>> return false; >>>> } >>>> =20 >>>> +static bool sccb_has_valid_boundary(uint64_t sccb_addr, uint32_t co= de, >>>> + SCCBHeader *header) >>>> +{ >>>> + uint64_t current_len =3D sccb_addr + be16_to_cpu(header->length= ); >>>> + uint64_t allowed_len =3D (sccb_addr & PAGE_MASK) + PAGE_SIZE; = >>> >>> Those are addresses not length indications and the names should refle= ct >>> that. =20 >> >> True >> >>> Also don't we need to use PAGE_SIZE - 1? >>> =20 >> >> Technically we need to -1 on both sides since length denotes the size = of >> the sccb in bytes, not the max address. >> >> How about this: >> >> s/current_len/sccb_max_addr >> s/allowed_len/sccb_boundary >=20 > +1, like the names. >=20 >> >> -1 to sccb_max_addr >> >> Change the check to: sccb_max_addr < sccb_boundary >> >> ? >> >>> I'm still trying to wake up, so take this with a grain of salt. >>> =20 >> >> No worries. I appreciate the review nonetheless :) >> >>>> + >>>> + switch (code & SCLP_CMD_CODE_MASK) { >>>> + default: >>>> + if (current_len <=3D allowed_len) { >>>> + return true; >>>> + } >>>> + } >>>> + header->response_code =3D cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIO= LATION); >>>> + return false; >>>> +} >>>> + >>>> +/* Calculates sufficient SCCB length to store a full Read SCP/CPU r= esponse */ >>>> +static bool sccb_has_sufficient_len(SCCB *sccb, int num_cpus, int d= ata_len) >>>> +{ >>>> + int required_len =3D data_len + num_cpus * sizeof(CPUEntry); >>>> + >>>> + if (be16_to_cpu(sccb->h.length) < required_len) { >>>> + sccb->h.response_code =3D cpu_to_be16(SCLP_RC_INSUFFICIENT_= SCCB_LENGTH); >>>> + return false; >>>> + } >>>> + return true; >>>> +} =20 >>> >>> Hm, from the function name alone I'd not have expected it to also set= >>> the response code. >>> =20 >> >> It also sets the required length in the header for an extended-length >> sccb. Perhaps this function name doesn't hold up well. >> >> Does sccb_check_sufficient_len make more sense? >=20 > To me it does. >=20 >> >> I think the same could be said of the boundary check function, which >> also sets the response code. >> >> What about setting the response code outside the function, similar to >> what sclp_comand_code_valid does? >=20 > Whatever results in the least code churn to make it consistent ;) >=20 >> >>>> + >>>> static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, = int *count) >>>> { >>>> uint8_t features[SCCB_CPU_FEATURE_LEN] =3D { 0 }; >>>> @@ -66,6 +94,16 @@ static void prepare_cpu_entries(MachineState *ms,= CPUEntry *entry, int *count) >>>> } >>>> } >>>> =20 >>>> +/* >>>> + * The data length denotes the start of the struct to where the fir= st >>>> + * CPU entry is to be allocated. This value also denotes the offset= _cpu >>>> + * field. >>>> + */ >>>> +static int get_read_scp_info_data_len(void) >>>> +{ >>>> + return offsetof(ReadInfo, entries); >>>> +} =20 >>> >>> Not sure what the policy for this is, but maybe this can go into a >>> header file? >>> David and Conny will surely make that clear to me :) >>> =20 >> >> Not sure either. If anything it might be a good candidate for an inlin= e >> function. >=20 > If we don't process read info outside of this file, no need to move it > to a header. The compiler is probably also smart enough to inline it on= > its own, I guess. >=20 >=20 I'm also ok with the names and the rest --e5s5OZqfvRUhatcbhJPVtjYtw4xlFloM4-- --eRln5ziRD2q6Rn1DegXOXUkRvoqM4u0Vr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEwGNS88vfc9+v45Yq41TmuOI4ufgFAl7Lo8UACgkQ41TmuOI4 ufgCkA/+OifwRI4oHarwf1uIX9mj7OtworMePPwdPxfn5ul+OGX6ZmGhNQC197Zc 3cXQlcUehpCCWahBpzqZnYjYWgqwdhjHnTsTqXIrkvJsDVt+k6fOBW1rFFuWg+PE d85AH06D0sxuIK+mU/ZPDNwCnSt7f9/B8DpwgYsnSooOEMfugjT0ods+rIO0uBiT uPZFu3MfKYHGKF/5AdlfJh4VlrsMJ1xy+tAgbkG/e7hTf2WOBeSp6zahqVdPqblp QTKgPlsGu/NEeykWy0lUlGtQG6v8NHfDE5143btFmT7qp1hGn2DqUPvuEdbvJqnz P44Slmt0WjVbt7q3W1wsPPRIbC1PvaZebX76FHM+DvgELzLzGJ8p4CixBtva21OK oeLVU8LptmJrsIkncL1MjzlhtOzfOOd4tDOvyIikwBeUP2PrmPQXmnbJ1fD76F6i NW3xCu3KzL+FW5dwgw+ivPvp7NmPQVHUWBGim5EOHeLncDGB0c7cyVK+8ZnuTLTa PNSmKXJGgh8xaZTj4JJTv4YxBORwqccNUflnlUCvWjd2D9Yz9ixjjeYMyNmHMX7u Er8i2J/HpkqevTDo8YqUMnvRp6jM/Gleswo9JqIFY8eHLUrOPbEkXF9XhjHR5Lr0 ET05m9MD5ZIecdMwQrK/7DZ2uL+AGTY90Wj9Bu2jK2JbgQAW6sw= =m4PZ -----END PGP SIGNATURE----- --eRln5ziRD2q6Rn1DegXOXUkRvoqM4u0Vr--