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Wed, 29 Jul 2026 09:53:19 +0000 (GMT) Received: from funtu2.ibm.com (unknown [9.111.165.15]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Jul 2026 09:53:19 +0000 (GMT) From: Harald Freudenberger To: dengler@linux.ibm.com, fcallies@linux.ibm.com, ifranzki@linux.ibm.com Cc: freude@linux.ibm.com, linux-s390@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev Subject: [PATCH v7 2/5] s390/zcrypt: Improve CCA CPRB length and overflow checks Date: Wed, 29 Jul 2026 11:53:15 +0200 Message-ID: <20260729095318.184141-3-freude@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260729095318.184141-1-freude@linux.ibm.com> References: <20260729095318.184141-1-freude@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI5MDA4MCBTYWx0ZWRfX0MsJ18Yi+Bh+ m4zr9IFah/2JaLQ8/M1aLRb2h7ugNqdVEjCChM2WCIe/ksp3I/O6r3sxm1TiIMU6Jezct6hZzj3 EUbxgMo3sMqQBDC9hxc4CbXKRVJBdBw= X-Proofpoint-GUID: L_X2JZVVk25TG5JnwtJmZTtD5iV-sEu2 X-Proofpoint-ORIG-GUID: L_X2JZVVk25TG5JnwtJmZTtD5iV-sEu2 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI5MDA4MCBTYWx0ZWRfXwaO7KdXb2G/F KZWyW5C5yFnr8Bcg96qTcFP0NkY/ut9mc9VMl3AC7R9zifRMcsxWMNnA5/lkS+NqesGTJGnFi6c tGR+SqPcLt2rWDzV+vlEq+lFIOCbYF0x/t89vAo3SZcx7q52N33ez/NJGISrQouNOtJwdhV6tHG zZIAA9YSMWyDmptglxiA6hVITdpTIB4NitwkfoE0RfJzmscTRADt3Hgtv0vrx1JrfIYhIIsLp6Q 29Mt+ZQkLlKzdZw8uA0vCjQnurhNpVUu1o2BTr153tbZSk4u5HifTAeNCQeEbm7MG4he3yM9YxZ xJMobvI3umwtG8AhK1UdpsFfBuOv/ZUKNjSS4Zjggit/g6FEJ3vPbylNRtL+NvN7A8a9C6pHPS/ /OGleX6shhTWj5L5pNePoyMt7aMN5EO/ANXciGLPkUXBnpJmEpRwR/ESfap/JLezZPFE10AJ1jm tsELKHjppsdw/Qa8Xfg== X-Authority-Analysis: v=2.4 cv=X5Vi7mTe c=1 sm=1 tr=0 ts=6a69cd94 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VnNF1IyMAAAA:8 a=A9_4VoiraDeQe4jIP7EA:9 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=2026-07-29_03,2026-07-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 malwarescore=0 spamscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607290080 The xcrb_msg_to_type6cprb_msgx() function lacks proper input validation, creating security vulnerabilities: 1. Integer overflow after CEIL4 alignment: Signed int variables could overflow during 4-byte boundary alignment, causing undersized buffer allocations or incorrect bounds checking. 2. Missing minimum size validation: The CPRBX structure is copied from userspace without verifying sufficient buffer length. Undersized buffers cause uninitialized memory access when reading structure fields like cprbx.cprb_len and cprbx.domain. 3. Arithmetic overflow in sum calculations: Adding control block and data block sizes could overflow, bypassing size checks and enabling buffer overflows. Fix by using size_t for length calculations, adding U32_MAX boundary checks after alignment, validating minimum control block size before copying from userspace, and detecting sum calculation overflows. Signed-off-by: Harald Freudenberger --- drivers/s390/crypto/zcrypt_msgtype6.c | 78 +++++++++++++-------------- 1 file changed, 36 insertions(+), 42 deletions(-) diff --git a/drivers/s390/crypto/zcrypt_msgtype6.c b/drivers/s390/crypto/zcrypt_msgtype6.c index 40f72cdf284d..fb37e28c8242 100644 --- a/drivers/s390/crypto/zcrypt_msgtype6.c +++ b/drivers/s390/crypto/zcrypt_msgtype6.c @@ -342,49 +342,40 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg, }; } __packed * msg = ap_msg->msg; - int rcblen = CEIL4(xcrb->request_control_blk_length); - int req_sumlen, resp_sumlen; - char *req_data = ap_msg->msg + sizeof(struct type6_hdr) + rcblen; - char *function_code; + size_t req_cblen, rep_cblen, req_sumlen, rep_sumlen; + char *function_code, *req_data; - if (CEIL4(xcrb->request_control_blk_length) < - xcrb->request_control_blk_length) - return -EINVAL; /* overflow after alignment*/ - - /* length checks */ + /* request length and overflow checks */ + if (xcrb->request_control_blk_length < sizeof(struct CPRBX)) + return -EINVAL; + req_cblen = CEIL4((size_t)xcrb->request_control_blk_length); + if (req_cblen > U32_MAX) + return -EINVAL; ap_msg->len = sizeof(struct type6_hdr) + - CEIL4(xcrb->request_control_blk_length) + - xcrb->request_data_length; + req_cblen + xcrb->request_data_length; if (ap_msg->len > ap_msg->bufsize) return -EINVAL; - - /* - * Overflow check - * sum must be greater (or equal) than the largest operand - */ - req_sumlen = CEIL4(xcrb->request_control_blk_length) + - xcrb->request_data_length; - if ((CEIL4(xcrb->request_control_blk_length) <= - xcrb->request_data_length) ? + req_sumlen = req_cblen + xcrb->request_data_length; + if (req_sumlen > U32_MAX) + return -EINVAL; + if (req_cblen <= xcrb->request_data_length ? req_sumlen < xcrb->request_data_length : - req_sumlen < CEIL4(xcrb->request_control_blk_length)) { + req_sumlen < req_cblen) { return -EINVAL; } - if (CEIL4(xcrb->reply_control_blk_length) < - xcrb->reply_control_blk_length) - return -EINVAL; /* overflow after alignment*/ - - /* - * Overflow check - * sum must be greater (or equal) than the largest operand - */ - resp_sumlen = CEIL4(xcrb->reply_control_blk_length) + - xcrb->reply_data_length; - if ((CEIL4(xcrb->reply_control_blk_length) <= - xcrb->reply_data_length) ? - resp_sumlen < xcrb->reply_data_length : - resp_sumlen < CEIL4(xcrb->reply_control_blk_length)) { + /* reply length and overflow checks */ + if (xcrb->reply_control_blk_length < sizeof(struct CPRBX)) + return -EINVAL; + rep_cblen = CEIL4((size_t)xcrb->reply_control_blk_length); + if (rep_cblen > U32_MAX) + return -EINVAL; + rep_sumlen = rep_cblen + xcrb->reply_data_length; + if (rep_sumlen > U32_MAX) + return -EINVAL; + if (rep_cblen <= xcrb->reply_data_length ? + rep_sumlen < xcrb->reply_data_length : + rep_sumlen < rep_cblen) { return -EINVAL; } @@ -393,7 +384,7 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg, memcpy(msg->hdr.agent_id, &xcrb->agent_ID, sizeof(xcrb->agent_ID)); msg->hdr.tocardlen1 = xcrb->request_control_blk_length; if (xcrb->request_data_length) { - msg->hdr.offset2 = msg->hdr.offset1 + rcblen; + msg->hdr.offset2 = msg->hdr.offset1 + req_cblen; msg->hdr.tocardlen2 = xcrb->request_data_length; } msg->hdr.fromcardlen1 = xcrb->reply_control_blk_length; @@ -404,8 +395,8 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg, xcrb->request_control_blk_addr, xcrb->request_control_blk_length)) return -EFAULT; - if (msg->cprbx.cprb_len + sizeof(msg->hdr.function_code) > - xcrb->request_control_blk_length) + /* copy subfunction code into AP msg type 6 function code field */ + if (msg->cprbx.cprb_len > req_cblen - sizeof(msg->hdr.function_code)) return -EINVAL; function_code = ((unsigned char *)&msg->cprbx) + msg->cprbx.cprb_len; memcpy(msg->hdr.function_code, function_code, @@ -437,10 +428,13 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg, } /* copy data block */ - if (xcrb->request_data_length && - z_copy_from_user(userspace, req_data, xcrb->request_data_address, - xcrb->request_data_length)) - return -EFAULT; + if (xcrb->request_data_length) { + req_data = ap_msg->msg + sizeof(struct type6_hdr) + req_cblen; + if (z_copy_from_user(userspace, req_data, + xcrb->request_data_address, + xcrb->request_data_length)) + return -EFAULT; + } return 0; } -- 2.43.0