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Wed, 29 Jul 2026 14:49:53 +0000 (GMT) Received: from ltc.linux.ibm.com (unknown [9.5.196.140]) by smtpav03.wdc07v.mail.ibm.com (Postfix) with ESMTP; Wed, 29 Jul 2026 14:49:53 +0000 (GMT) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Wed, 29 Jul 2026 16:49:53 +0200 From: Harald Freudenberger To: sashiko-reviews@lists.linux.dev Cc: linux-s390@vger.kernel.org, Alexander Gordeev , Heiko Carstens , Vasily Gorbik Subject: Re: [PATCH v2 1/1] s390/zcrypt: Fix missing mem scrub at clear key import in cca_clr2cipherkey() Reply-To: freude@linux.ibm.com Mail-Reply-To: freude@linux.ibm.com In-Reply-To: <20260729141220.E28071F000E9@smtp.kernel.org> References: <20260729140134.191448-1-freude@linux.ibm.com> <20260729140134.191448-2-freude@linux.ibm.com> <20260729141220.E28071F000E9@smtp.kernel.org> Message-ID: <6c3731e778b0882cf7f6c356d71fac83@linux.ibm.com> X-Sender: freude@linux.ibm.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 8IZEZIKWzAUuL6_Q_4LZC7uOChFAmGdJ X-Proofpoint-ORIG-GUID: 8IZEZIKWzAUuL6_Q_4LZC7uOChFAmGdJ X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI5MDEyMCBTYWx0ZWRfX4FNPSRjfXCEx XF7XKJTq74DNr6U1SDMFo66926qtgG9ta1CwGZ83XRZIF3DXfB2crFCxQ8+KdM+gH8g0qGtIQOx JMc0ebXeXv0z4h87eId6kV2rxxMJQtg= X-Authority-Analysis: v=2.4 cv=dYuwG3Xe c=1 sm=1 tr=0 ts=6a6a1314 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=kj9zAlcOel0A:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=5OT_ED_vbPaHr4bv3HIA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI5MDEyMCBTYWx0ZWRfX9uLNsCTxrz9T oe4yEk+7ccWTVo/zUtCVra1hQ1p83PKMIc62rThUvyWCCgDtR5XFjt8QoxHPziyy29CJKuJWaLZ bh04EWkXl7hxTRNW2B6OYeYnpbDpU0SzyXd24ilNE+K2kI2vxXaT85uKBdhPuH4F6hRo2PnvYKL jiIrnhXYfyc2oY95kVtDZsinKSFhLNSacH3aEfw2h5l1homcIUsFHeW5AINsXVBEWHDhdbIFsWe 6stmROs0Z/6wfWtv5OxamZazZIF8wjqBZQyDx0GuX8ElNYHVBhtW9Fi0GjHGSjV022FGrvauAZo iy5YeCYlKf7Tawu0Ps/0bnF3m2KBX7+Ysvj5bd6KmX9kBG3VqgTnDb8ly1QRGWPMK3HsvbFteEO YqYv2ihXJ+o7Qdt+EiibeeuaPqzrigB8Fspn/1vQ0S49Kje+qzCBITeROGoalwpTXI5/tU4qEPf KYH7ZgKEFfdKI4l96iA== 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_06,2026-07-28_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 clxscore=1015 phishscore=0 malwarescore=0 spamscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607290120 On 2026-07-29 16:12, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential > issue(s) to consider: > > Pre-existing issues: > - [High] Unvalidated length field `t->len` from an untrusted hardware > response leads to severe out-of-bounds memory accesses during > `memcpy()`. > -- > > --- Patch [1]: [PATCH v2 1/1] s390/zcrypt: Fix missing mem scrub at > clear key import in cca_clr2cipherkey() --- > commit 0678dd664c1b50d9a38dff946d27b4823de1e205 > Author: Harald Freudenberger > > s390/zcrypt: Fix missing mem scrub at clear key import in > cca_clr2cipherkey() > > This commit adds a parameter to _ip_cprb_helper() to scrub the CPRB > buffer > after processing clear key material. It also adds explicit zeroing of > the > buffers before freeing them in cca_clr2cipherkey() to prevent sensitive > data exposure. > >> diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c >> b/drivers/s390/crypto/zcrypt_ccamisc.c >> index 84936a795b956..9cf268efd4abf 100644 >> --- a/drivers/s390/crypto/zcrypt_ccamisc.c >> +++ b/drivers/s390/crypto/zcrypt_ccamisc.c > [ ... ] >> @@ -1111,7 +1112,7 @@ static int _ip_cprb_helper(u16 cardnr, u16 >> domain, >> *key_token_size = t->len; > > [Severity: High] > This is a pre-existing issue, but is it possible for a compromised or > malfunctioning hardware device to return a maliciously crafted response > length in t->len? > > In _ip_cprb_helper(), the unvalidated t->len from the hardware response > is > directly used as the length for copying just before this line: > > t = (struct cipherkeytoken *)prepparm->kb.tlv1.key_token; > memcpy(key_token, t, t->len); > *key_token_size = t->len; > > Without bounds checking against the actual buffer size, could this lead > to an > out-of-bounds read from the device response buffer and an out-of-bounds > write > into the key_token buffer? > > Also, on subsequent iterations in cca_clr2cipherkey(), the poisoned > *key_token_size is used to construct the next request: > > preq_key_block->tlv1.len = sizeof(preq_key_block->tlv1) + n; > preq_key_block->tlv1.flag = 0x0030; > memcpy(preq_key_block->tlv1.key_token, key_token, *key_token_size); > > Does this cause another unbounded copy into the smaller parameter > buffer during > the next loop iteration? > >> >> out: >> - free_cprbmem(mem, PARMBSIZE, false, xflags); >> + free_cprbmem(mem, PARMBSIZE, scrub, xflags); >> return rc; >> } This is a valid finding but will be addressed with another patch series.