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Fri, 8 Dec 2023 14:14:03 GMT Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D6F0D2004B; Fri, 8 Dec 2023 14:14:02 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8C55A20040; Fri, 8 Dec 2023 14:14:01 +0000 (GMT) Received: from [9.171.76.38] (unknown [9.171.76.38]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 8 Dec 2023 14:14:01 +0000 (GMT) Message-ID: <4f0eb4b4d4f6830f39555dc8a35f6ff88d6f8e63.camel@linux.ibm.com> Subject: Re: [PATCH v2 19/33] lib/zlib: Unpoison DFLTCC output buffers From: Ilya Leoshkevich To: Alexander Potapenko Cc: Alexander Gordeev , Andrew Morton , Christoph Lameter , David Rientjes , Heiko Carstens , Joonsoo Kim , Marco Elver , Masami Hiramatsu , Pekka Enberg , Steven Rostedt , Vasily Gorbik , Vlastimil Babka , Christian Borntraeger , Dmitry Vyukov , Hyeonggon Yoo <42.hyeyoo@gmail.com>, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Roman Gushchin , Sven Schnelle , Mikhail Zaslonko Date: Fri, 08 Dec 2023 15:14:01 +0100 In-Reply-To: References: <20231121220155.1217090-1-iii@linux.ibm.com> <20231121220155.1217090-20-iii@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.48.4 (3.48.4-1.fc38) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: hoRrnOaWeMBzUuRaToAfGaqdk4G_1Fq_ X-Proofpoint-ORIG-GUID: Q-kY3HiQsqOVFy02f6bQ466_FlOXn4Ht X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-08_09,2023-12-07_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 impostorscore=0 mlxscore=0 spamscore=0 adultscore=0 phishscore=0 bulkscore=0 suspectscore=0 malwarescore=0 mlxlogscore=774 lowpriorityscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312080117 X-Rspamd-Queue-Id: A6FBD40013 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: knbe4o6sgh1ck879n34mpwns8e7jbpq9 X-HE-Tag: 1702044853-448417 X-HE-Meta: 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 zsUieKrC Rl7NWcLogUueYgV7MOR76tmM6Iu0b9RxR3ZhyhtXroJSiAiT4jQVcimqrAAdcFVQDs0SchEXLKqS0vsAAaWsLZEgiVUB/ki4CtlDi9RsqmQon18KM6K1l3HC7SpeCZL3386VTkQToapuD9QkGx98TMBGkYiaFlYJ6Y7jTppMWaY3D3NQ1McMWaR4B/zYS/al/uD3TjEvQ4hj6ZfQqHDm5WeIXG41Jpx6EH5e4oucs+jx+kjZDD50JSyhu7zmYtqd++Mvok6B5owPu5oc/nbHqSx4nbotm9WukgYOGYBgsoOEp4IgW5t+8FbFPkrRTQ8fcU01D X-Bogosity: Ham, tests=bogofilter, spamicity=0.000962, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 2023-12-08 at 14:32 +0100, Alexander Potapenko wrote: > On Tue, Nov 21, 2023 at 11:07=E2=80=AFPM Ilya Leoshkevich > wrote: > >=20 > > The constraints of the DFLTCC inline assembly are not precise: they > > do not communicate the size of the output buffers to the compiler, > > so > > it cannot automatically instrument it. >=20 > KMSAN usually does a poor job instrumenting inline assembly. > Wouldn't be it better to switch to pure C ZLIB implementation, making > ZLIB_DFLTCC depend on !KMSAN? Normally I would agree, but the kernel DFLTCC code base is synced with the zlib-ng code base to the extent that it uses the zlib-ng code style instead of the kernel code style, and MSAN annotations are already a part of the zlib-ng code base. So I would prefer to keep them for consistency. The code is also somewhat tricky in the are of buffer management, so I find it beneficial to have it checked for uninitialized memory accesses.