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Mon, 20 Jul 2026 20:19:32 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav06.fra02v.mail.ibm.com (Postfix) with SMTP; Mon, 20 Jul 2026 20:19:32 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 4958) id BBE77162788; Mon, 20 Jul 2026 22:19:32 +0200 (CEST) From: Eric Farman To: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Matthew Rosato , Halil Pasic , Christian Borntraeger , Eric Farman , stable@vger.kernel.org Subject: [PATCH v2 3/7] s390/vfio_ccw: fix out of bounds check on CCW array Date: Mon, 20 Jul 2026 22:19:27 +0200 Message-ID: <20260720201931.976660-4-farman@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260720201931.976660-1-farman@linux.ibm.com> References: <20260720201931.976660-1-farman@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzIwMDIyMCBTYWx0ZWRfX9GCO7eItBKjG CUq/LLmxNeUV2/h4Mkf+zZZXmT+NRiLe1mmroL4ZP21LuJhOGqb4Icr5qD3Byt7tavmUBzFQxCr igxt8geA1VdUZUNsnOREOHurkLh9F1laOiheFzTopp2qnDCeqdgCn1+fVwECA/Q8KfJmqbTS2H+ uAHzYFD3XYc+sJQkm4+zo7u5Q2dhoPs6bjUspqUbdNKsHnWVRroypr9Pb2BYEN2aQAA8v5okU8E et8wVjDEwRa7jLbw2SP3hu32QVBj+JxmLP2jHSmOaujL+4lMRq3mFjibNKEQEAsYHoWOHBw9Fgo 1izYihCq6zL8aMRfUDn8/xevNiF02wKmlfIshhhvBXEAXkEeUd2lom9kxj7EnbSTU8i6sFtsEZK iz6B/VOY7dtvBqxr2WTOjNGu524EK4mhsNra4rSr4kKg5RFn8ytvc+DsEHayadi6+vmVwmgyGkZ Cw5NoCy8S+QnLwvH7SQ== X-Proofpoint-GUID: 0cJz5U8iJGrGttvGpbkohrBSySy3BDog X-Authority-Analysis: v=2.4 cv=MelcfZ/f c=1 sm=1 tr=0 ts=6a5e82d9 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Ztfy0_AA8xUuwmIluScA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzIwMDIyMCBTYWx0ZWRfX2zlKfnsYuJfr dvI1tZnOh6hpWFMWrdRg8myvjs8Ra3WUpWJAXJP9oKQetWa2+VmI2xyDwsTeaSb80T+lDOU2/et rfOQS6fnSG4+Dpl23Z9T6PtD1qIrhGI= X-Proofpoint-ORIG-GUID: 0cJz5U8iJGrGttvGpbkohrBSySy3BDog X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-20_05,2026-07-20_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 spamscore=0 clxscore=1015 malwarescore=0 phishscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607200220 The routine ccwchain_calc_length() counts the number of channel command words (CCWs) that are chained together in a single channel program, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs. The loop itself is "do..while (count < 257)", and while the logic in is_cpa_within_range() correctly adjusts between the 0-index array of CCWs and the count of CCWs starting at 1, this means it would look at a possible 257th CCW before ending the loop and (correctly) returning an error. Fix this by restructuring the loop to break as soon as 256 CCWs (thus indexes 0-255) are examined, without looking at memory outside the range. Fixes: 0a19e61e6d4c ("vfio: ccw: introduce channel program interfaces") Cc: stable@vger.kernel.org Signed-off-by: Eric Farman --- drivers/s390/cio/vfio_ccw_cp.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_c= p.c index 7abdebd8f7c3..ce61858c82eb 100644 --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -393,11 +393,14 @@ static int ccwchain_calc_length(u64 iova, struct ch= annel_program *cp) if (!ccw_is_chain(ccw) && !is_tic_within_range(ccw, iova, cnt)) break; =20 - ccw++; - } while (cnt < CCWCHAIN_LEN_MAX + 1); + /* Exit the loop when we reach the maximum */ + if (cnt >=3D CCWCHAIN_LEN_MAX) { + cnt =3D -EINVAL; + break; + } =20 - if (cnt =3D=3D CCWCHAIN_LEN_MAX + 1) - cnt =3D -EINVAL; + ccw++; + } while (1); =20 return cnt; } --=20 2.53.0