From patchwork Tue Nov 21 22:01:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ilya Leoshkevich X-Patchwork-Id: 13463654 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="PE5rvZBX" Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 241A310FA; Tue, 21 Nov 2023 14:03:01 -0800 (PST) Received: from pps.filterd (m0353723.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3ALLNPww004545; Tue, 21 Nov 2023 22:02:36 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=8ulWVBzZN7+Eh8v1+pwjF8+VtqCEXlOniIAURZ6XsF0=; b=PE5rvZBXzaG95ry5yGOcNSiMYaQFq12iYCi+qO3gKFuw+f4New7PahfJqdxUA7kzEyaZ ziDpt11jKABTJS7QTUye23eQJXODwqDvsPJgOkBb+OvBbmEtBxODrlYYqBc9/7wmvaZc HNSxIfLq+ufNE6TQx50gPwWB/DiEysN4YQxD3x7HXy1MQFdwGNzdLi+SlX8E8cuqrCQf LdLFcxu2JgvEfcLCmbU0r3qmIVbhY5IVFi1+vm9tnI25RuyYLjhEaExI91YXg0Q24u7L Xqm0vqqOjUw2qV1vkIhSBwq8UKTR7YcEB3a1pdwR6vBPmz7sA1/b/mUb3GyxZtrP945U Lw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3uh4dw0vpy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Nov 2023 22:02:35 +0000 Received: from m0353723.ppops.net (m0353723.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 3ALLmrxa011402; Tue, 21 Nov 2023 22:02:35 GMT Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3uh4dw0vnt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Nov 2023 22:02:35 +0000 Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 3ALLng01010753; Tue, 21 Nov 2023 22:02:33 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3uf93kujq8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 21 Nov 2023 22:02:32 +0000 Received: from smtpav06.fra02v.mail.ibm.com (smtpav06.fra02v.mail.ibm.com [10.20.54.105]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 3ALM2TVO53018986 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Nov 2023 22:02:29 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AEE5720065; Tue, 21 Nov 2023 22:02:29 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 47AD12005A; Tue, 21 Nov 2023 22:02:28 +0000 (GMT) Received: from heavy.boeblingen.de.ibm.com (unknown [9.179.23.98]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 21 Nov 2023 22:02:28 +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 v2 14/33] kmsan: Support SLAB_POISON Date: Tue, 21 Nov 2023 23:01:08 +0100 Message-ID: <20231121220155.1217090-15-iii@linux.ibm.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231121220155.1217090-1-iii@linux.ibm.com> References: <20231121220155.1217090-1-iii@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: Dk2pSCnouKh_Mi2qevl2yd6RHaco_mCa X-Proofpoint-ORIG-GUID: IyYeO4Ls9Zhe1WDu9j0NdlseK0tlnQN6 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-11-21_12,2023-11-21_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 mlxlogscore=999 spamscore=0 suspectscore=0 phishscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 impostorscore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311060000 definitions=main-2311210172 Avoid false KMSAN negatives with SLUB_DEBUG by allowing kmsan_slab_free() to poison the freed memory, and by preventing init_object() from unpoisoning new allocations. The usage of memset_no_sanitize_memory() does not degrade the generated code quality. There are two alternatives to this approach. First, init_object() can be marked with __no_sanitize_memory. This annotation should be used with great care, because it drops all instrumentation from the function, and any shadow writes will be lost. Even though this is not a concern with the current init_object() implementation, this may change in the future. Second, kmsan_poison_memory() calls may be added after memset() calls. The downside is that init_object() is called from free_debug_processing(), in which case poisoning will erase the distinction between simply uninitialized memory and UAF. Signed-off-by: Ilya Leoshkevich --- mm/kmsan/hooks.c | 2 +- mm/slub.c | 10 ++++++---- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 7b5814412e9f..7a30274b893c 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -76,7 +76,7 @@ void kmsan_slab_free(struct kmem_cache *s, void *object) return; /* RCU slabs could be legally used after free within the RCU period */ - if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))) + if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) return; /* * If there's a constructor, freed memory must remain in the same state diff --git a/mm/slub.c b/mm/slub.c index 63d281dfacdb..169e5f645ea8 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1030,7 +1030,8 @@ static void init_object(struct kmem_cache *s, void *object, u8 val) unsigned int poison_size = s->object_size; if (s->flags & SLAB_RED_ZONE) { - memset(p - s->red_left_pad, val, s->red_left_pad); + memset_no_sanitize_memory(p - s->red_left_pad, val, + s->red_left_pad); if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) { /* @@ -1043,12 +1044,13 @@ static void init_object(struct kmem_cache *s, void *object, u8 val) } if (s->flags & __OBJECT_POISON) { - memset(p, POISON_FREE, poison_size - 1); - p[poison_size - 1] = POISON_END; + memset_no_sanitize_memory(p, POISON_FREE, poison_size - 1); + memset_no_sanitize_memory(p + poison_size - 1, POISON_END, 1); } if (s->flags & SLAB_RED_ZONE) - memset(p + poison_size, val, s->inuse - poison_size); + memset_no_sanitize_memory(p + poison_size, val, + s->inuse - poison_size); } static void restore_bytes(struct kmem_cache *s, char *message, u8 data,