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Wed, 7 Oct 2026 11:41:59 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav01.fra02v.mail.ibm.com (Postfix) with SMTP; Wed, 7 Oct 2026 11:41:59 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 55669) id 96E63160B43; Wed, 07 Oct 2026 13:41:58 +0200 (CEST) From: Alexander Gordeev To: Gerald Schaefer , Heiko Carstens , Christian Borntraeger , Vasily Gorbik , Claudio Imbrenda , Andrey Ryabinin Cc: Muhammad Usama Anjum , linux-s390@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Subject: [PATCH v8 14/15] mm/kasan: Introduce helpers for lazy MMU mode sanitizer Date: Wed, 7 Oct 2026 13:41:57 +0200 Message-ID: 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-Proofpoint-Spam-Info: AW1haW4tMjYxMDA3MDA0NiBTYWx0ZWRfX5DPD1vMEIRzd xleVCrHSsImUVSa9k8+U0VNhK6NPZ4rkedvwRN+pHGmVxse85mJThumaN735FZQ7qT+ZLwoW7Gv lMQezcdm0GX0Rr+40UeLZMYz0OG7Wjs= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDA3MDA0NiBTYWx0ZWRfX7g2X1iUGlT58 qoF4bC6WFYXBZ9MVGwR7Pf5b2cTZiR08BPqu1ISG5mhomOu15rPA61t7AFAxvef2tBggMTl7U/L G3va4UQIxlb6J7zIR7zRzrYd3OwyvaC/6bM5yPlAkKc9gFNMzKeeatuVkwgWaz7Yv8XuvMZk5FA SpJy6eje6TISppIe276PGJ8Ik+QNlq19GHXhc4o77ZcoAeXMqJ1bREhgD6F9YL+gE/ZBEI4WaF0 QYeFhaRABOMEJA0rqjEFHQ9YEjHl172hGhHOE3IfyVoXl+RpJYRsivy3QSn+96F0fzafgx+PgwJ eq5G0EB1bBEdP71UuonqU8soJz3Z26sMWYFy/rpiIpZPpMOqCHDiCPZ8zJP9b2SzXpYNbUTFeRd LyBl2WjC6/Nk/j+0TPaoSxEqbfdKhE0KZIeaRAdj0owYPBtSOvVCx8+plUOjRCKDZV5mLWxi1jz Bhf/XJvsIMWV1oplDRw== X-Proofpoint-GUID: Dicociyuch-2AgzrCM5waLHvo_mDtbuk X-Authority-Analysis: v=2.4 cv=UNRIjyfy c=1 sm=1 tr=0 ts=6ac6300c cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=bocLCBUijn_7D3B78osA:9 X-Proofpoint-ORIG-GUID: ReRFxk3b6iDzlnLcBGQVeXTs5QFTGZJn X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-07_04,2026-10-06_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 adultscore=0 bulkscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610070046 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 | 19 +++++++++++++++++-- mm/kasan/common.c | 14 ++++++++++++++ mm/kasan/kasan.h | 2 ++ mm/kasan/report_generic.c | 3 +++ 4 files changed, 36 insertions(+), 2 deletions(-) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index ff41949c0ac0..01f710f03114 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -6,6 +6,7 @@ #include #include #include +#include #include #include =20 @@ -35,8 +36,6 @@ typedef unsigned int __bitwise kasan_vmalloc_flags_t; =20 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) =20 -#include - /* Software KASAN implementations use shadow memory. */ =20 #ifdef CONFIG_KASAN_SW_TAGS @@ -134,6 +133,20 @@ static __always_inline void kasan_poison_slab(struct= slab *slab) __kasan_poison_slab(slab); } =20 +void __kasan_poison_pte(hw_pte_t *pte, int nr); +static __always_inline void kasan_poison_pte(hw_pte_t *pte, int nr) +{ + if (kasan_enabled()) + __kasan_poison_pte(pte, nr); +} + +void __kasan_unpoison_pte(hw_pte_t *pte, int nr); +static __always_inline void kasan_unpoison_pte(hw_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 +427,8 @@ 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(hw_pte_t *pte, int nr) {} +static inline void kasan_unpoison_pte(hw_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 7d21c4db68d2..f3cbbeb8ad0e 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -174,6 +174,20 @@ void __kasan_poison_slab(struct slab *slab) KASAN_SLAB_REDZONE, false); } =20 +void __kasan_poison_pte(hw_pte_t *pte, int nr) +{ + if (IS_ALIGNED(sizeof(*pte), KASAN_GRANULE_SIZE)) + kasan_poison(pte, sizeof(*pte) * nr, KASAN_LAZY_MMU_PTE, false); +} +EXPORT_SYMBOL_GPL(__kasan_poison_pte); + +void __kasan_unpoison_pte(hw_pte_t *pte, int nr) +{ + if (IS_ALIGNED(sizeof(*pte), KASAN_GRANULE_SIZE)) + kasan_unpoison(pte, sizeof(*pte) * nr, false); +} +EXPORT_SYMBOL_GPL(__kasan_unpoison_pte); + 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