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Wed, 13 Dec 2023 23:36:33 GMT Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4F08920043; Wed, 13 Dec 2023 23:36:33 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DCEF820040; Wed, 13 Dec 2023 23:36:31 +0000 (GMT) Received: from heavy.boeblingen.de.ibm.com (unknown [9.171.70.156]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 13 Dec 2023 23:36:31 +0000 (GMT) From: Ilya Leoshkevich To: Alexander Gordeev , Alexander Potapenko , Andrew Morton , Christoph Lameter , David Rientjes , Heiko Carstens , Joonsoo Kim , Marco Elver , Masami Hiramatsu , Pekka Enberg , Steven Rostedt , Vasily Gorbik , Vlastimil Babka Cc: 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 , Ilya Leoshkevich Subject: [PATCH v3 15/34] mm: slub: Unpoison the memchr_inv() return value Date: Thu, 14 Dec 2023 00:24:35 +0100 Message-ID: <20231213233605.661251-16-iii@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231213233605.661251-1-iii@linux.ibm.com> References: <20231213233605.661251-1-iii@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: kPY9E1UvYdSAN4yA0WGECmQaAwtxBTWd X-Proofpoint-ORIG-GUID: zPDn9MZkVLtny7zKhboJlYnQt5V5Co18 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=2023-12-13_14,2023-12-13_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 impostorscore=0 clxscore=1015 adultscore=0 phishscore=0 mlxscore=0 bulkscore=0 suspectscore=0 spamscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2312130167 X-Rspamd-Queue-Id: 87BBCC0002 X-Rspam-User: X-Stat-Signature: 64h1ju4h466ok5mwbenz7wsz7ka16okn X-Rspamd-Server: rspam01 X-HE-Tag: 1702510605-837787 X-HE-Meta: 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 ludKOZ4f wi/Cmy2CgmbFbq0pociGk/IgeFdw4Tii2/ur5iE5bcldN9JW6M/IeVz0xllUTIsqtpU4jC00V4wtcZZ7wiRoN8GukkRRW3hIY2GHxAaQBp4M7vexOMINBCns6P/WaAvhsGeCNMotnAgy3OiWbKrKIjAPOUHH6WUV6tW2mQCm//auh7fVjtXOH65kegaZ96mKD9DwEujmsIpmbB6/oYpEKseIlvlsTyN3P4QYvNJFAL/elWt+klr5loLjV/Ga4ycJ4c6w+JprEaip9/Yc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000012, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Even though the KMSAN warnings generated by memchr_inv() are suppressed by metadata_access_enable(), its return value may still be poisoned. The reason is that the last iteration of memchr_inv() returns `*start != value ? start : NULL`, where *start is poisoned. Because of this, somewhat counterintuitively, the shadow value computed by visitSelectInst() is equal to `(uintptr_t)start`. The intention behind guarding memchr_inv() behind metadata_access_enable() is to touch poisoned metadata without triggering KMSAN, so unpoison its return value. Signed-off-by: Ilya Leoshkevich --- mm/slub.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index 2d29d368894c..802702748925 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1076,6 +1076,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab, metadata_access_enable(); fault = memchr_inv(kasan_reset_tag(start), value, bytes); metadata_access_disable(); + kmsan_unpoison_memory(&fault, sizeof(fault)); if (!fault) return 1; @@ -1182,6 +1183,7 @@ static void slab_pad_check(struct kmem_cache *s, struct slab *slab) metadata_access_enable(); fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder); metadata_access_disable(); + kmsan_unpoison_memory(&fault, sizeof(fault)); if (!fault) return; while (end > fault && end[-1] == POISON_INUSE) -- 2.43.0