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Mon, 13 Jul 2026 14:18:28 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with SMTP; Mon, 13 Jul 2026 14:18:28 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 55669) id F27DD162522; Mon, 13 Jul 2026 16:18:27 +0200 (CEST) From: Alexander Gordeev To: Gerald Schaefer , Heiko Carstens , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda , Andrey Ryabinin Cc: linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Kevin Brodsky , David Hildenbrand Subject: [PATCH v5 3/4] mm/kasan: Introduce helpers for lazy MMU mode sanitizer Date: Mon, 13 Jul 2026 16:18:26 +0200 Message-ID: <38a663eeccd060d961990baf65338e2f2550e580.1783945507.git.agordeev@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=fOcJG5ae c=1 sm=1 tr=0 ts=6a54f3b9 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=iFyILk1haAFnC_s91q8A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzEzMDE0OCBTYWx0ZWRfXy1I9EchAqqyO dXL8Pnx9oOjgJN/nfv563MDUqGvPiSRS+wsivCrOONCRp5LF4Wmhao9QoGBvrmws4VeUaGvfQ+t 8IEN1s2ncYpk9NV0roZqtfbTPZ/A9w2vMw4v+FUkwBzgrsTOqqnYMtenhKtnE8VbQ7+2FaPYSwt vR5YRrQvblKdKbvQK2pQvKcMTeAWpLtFxLlL5bMiEq19uexQ80E0sW6oK/038XoWzqht/ayBtPs 5fqxSr5vdpf8auvOq8OeAfc8lXHp6T7N71cqs0QDh3+RP4MmDFQuv61Hc2YAq8lIs7ZGi6XZYFu Y7oCIYYWkPp2b50gNY6c9X9ihTDboG3EQ2pGxtO673U0BPSZrNTkvW+BdcTAqcoeDAsZbXGyoWj XV2MXJAr+sP2/OXiSHL+YcCAcqLiGQFgUDgXpItrgSe9iIsD1DcK3uPSpWxWU+Jwck2KdDXYDvM gx6L3TOMbS7ZiRzCnYg== X-Proofpoint-Spam-Info: AW1haW4tMjYwNzEzMDE0OCBTYWx0ZWRfX2MXCilhzZkG5 0oHQF+aUOwwDmM7CK39kg+KtMEilOiDOb+lySdlR+A+AqGFsfZlnH/iFRgY/wWGIHjvHFVsTq0S mhq/Be1YZHBMCU0lxhcfUEbbaHX1VxQ= X-Proofpoint-GUID: fbeKGc689gDMosGxsekWQ_xt2MkGAW4U X-Proofpoint-ORIG-GUID: vqO7vk9TXadg0UNw7zBHzra_XtR5hBsV 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=2026-07-13_03,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 impostorscore=0 suspectscore=0 adultscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 phishscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607130148 Provide helpers that allow architectures implement illegitimate PTE direct accesses while the lazy MMU mode is enabled, such as: pte_t pte =3D *ptep; *ptep =3D pte; By contrast, these would have to be: pte_t pte =3D ptep_get(ptep); set_pte(ptep, pte); The direct PTE accesses pose a real issue on s390. Suggested-by: Ilya Leoshkevich Signed-off-by: Alexander Gordeev --- include/linux/kasan.h | 16 ++++++++++++++++ mm/kasan/common.c | 10 ++++++++++ mm/kasan/kasan.h | 2 ++ mm/kasan/report_generic.c | 3 +++ 4 files changed, 31 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index bf233bde68c7..deadf566b84a 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -134,6 +134,20 @@ static __always_inline void kasan_poison_slab(struct= slab *slab) __kasan_poison_slab(slab); } =20 +void __kasan_poison_pte(pte_t *pte, int nr); +static __always_inline void kasan_poison_pte(pte_t *pte, int nr) +{ + if (kasan_enabled()) + __kasan_poison_pte(pte, nr); +} + +void __kasan_unpoison_pte(pte_t *pte, int nr); +static __always_inline void kasan_unpoison_pte(pte_t *pte, int nr) +{ + if (kasan_enabled()) + __kasan_unpoison_pte(pte, nr); +} + void __kasan_unpoison_new_object(struct kmem_cache *cache, void *object)= ; /** * kasan_unpoison_new_object - Temporarily unpoison a new slab object. @@ -414,6 +428,8 @@ static inline bool kasan_unpoison_pages(struct page *= page, unsigned int order, return false; } static inline void kasan_poison_slab(struct slab *slab) {} +static inline void kasan_poison_pte(pte_t *pte, int nr) {} +static inline void kasan_unpoison_pte(pte_t *pte, int nr) {} static inline void kasan_unpoison_new_object(struct kmem_cache *cache, void *object) {} static inline void kasan_poison_new_object(struct kmem_cache *cache, diff --git a/mm/kasan/common.c b/mm/kasan/common.c index b7d05c2a6d93..cbf68680614e 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -163,6 +163,16 @@ void __kasan_poison_slab(struct slab *slab) KASAN_SLAB_REDZONE, false); } =20 +void __kasan_poison_pte(pte_t *pte, int nr) +{ + kasan_poison(pte, sizeof(*pte) * nr, KASAN_LAZY_MMU_PTE, false); +} + +void __kasan_unpoison_pte(pte_t *pte, int nr) +{ + kasan_unpoison(pte, sizeof(*pte) * nr, false); +} + void __kasan_unpoison_new_object(struct kmem_cache *cache, void *object) { kasan_unpoison(object, cache->object_size, false); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index fc9169a54766..1a2d18cdb21d 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -144,12 +144,14 @@ static inline bool kasan_requires_meta(void) #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocation= */ #define KASAN_SLAB_REDZONE 0xFC /* redzone for slab object */ #define KASAN_SLAB_FREE 0xFB /* freed slab object */ +#define KASAN_LAZY_MMU_PTE 0xFD /* direct pte access in lazy mmu mode *= / #define KASAN_VMALLOC_INVALID 0xF8 /* inaccessible space in vmap area *= / #else #define KASAN_PAGE_FREE KASAN_TAG_INVALID #define KASAN_PAGE_REDZONE KASAN_TAG_INVALID #define KASAN_SLAB_REDZONE KASAN_TAG_INVALID #define KASAN_SLAB_FREE KASAN_TAG_INVALID +#define KASAN_LAZY_MMU_PTE KASAN_TAG_INVALID #define KASAN_VMALLOC_INVALID KASAN_TAG_INVALID /* only used for SW_TAGS= */ #endif =20 diff --git a/mm/kasan/report_generic.c b/mm/kasan/report_generic.c index f5b8e37b3805..489d4a8d6902 100644 --- a/mm/kasan/report_generic.c +++ b/mm/kasan/report_generic.c @@ -113,6 +113,9 @@ static const char *get_shadow_bug_type(struct kasan_r= eport_info *info) case KASAN_SLAB_FREE_META: bug_type =3D "slab-use-after-free"; break; + case KASAN_LAZY_MMU_PTE: + bug_type =3D "lazy-mmu-pte-access"; + break; case KASAN_ALLOCA_LEFT: case KASAN_ALLOCA_RIGHT: bug_type =3D "alloca-out-of-bounds"; --=20 2.53.0