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[34.79.16.42]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45e037186e5sm212975035e9.5.2025.09.16.02.01.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Sep 2025 02:01:18 -0700 (PDT) From: Ethan Graham To: ethangraham@google.com, glider@google.com Cc: andreyknvl@gmail.com, andy@kernel.org, brauner@kernel.org, brendan.higgins@linux.dev, davem@davemloft.net, davidgow@google.com, dhowells@redhat.com, dvyukov@google.com, elver@google.com, herbert@gondor.apana.org.au, ignat@cloudflare.com, jack@suse.cz, jannh@google.com, johannes@sipsolutions.net, kasan-dev@googlegroups.com, kees@kernel.org, kunit-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lukas@wunner.de, rmoar@google.com, shuah@kernel.org, tarasmadan@google.com Subject: [PATCH v1 01/10] mm/kasan: implement kasan_poison_range Date: Tue, 16 Sep 2025 09:01:00 +0000 Message-ID: <20250916090109.91132-2-ethan.w.s.graham@gmail.com> X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog In-Reply-To: <20250916090109.91132-1-ethan.w.s.graham@gmail.com> References: <20250916090109.91132-1-ethan.w.s.graham@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 3327540019 X-Stat-Signature: 6qb1wtpr7kbom6dhnyazh7ymp3p3j449 X-Rspam-User: X-HE-Tag: 1758013280-267525 X-HE-Meta: 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 NIDhnkzg 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ethan Graham Introduce a new helper function, kasan_poison_range(), to encapsulate the logic for poisoning an arbitrary memory range of a given size, and expose it publically in . This is a preparatory change for the upcoming KFuzzTest patches, which requires the ability to poison the inter-region padding in its input buffers. No functional change to any other subsystem is intended by this commit. --- v3: - Enforce KASAN_GRANULE_SIZE alignment for the end of the range in kasan_poison_range(), and return -EINVAL when this isn't respected. --- Signed-off-by: Ethan Graham --- include/linux/kasan.h | 11 +++++++++++ mm/kasan/shadow.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 890011071f2b..cd6cdf732378 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -102,6 +102,16 @@ static inline bool kasan_has_integrated_init(void) } #ifdef CONFIG_KASAN + +/** + * kasan_poison_range - poison the memory range [@addr, @addr + @size) + * + * The exact behavior is subject to alignment with KASAN_GRANULE_SIZE, defined + * in : if @start is unaligned, the initial partial granule + * at the beginning of the range is only poisoned if CONFIG_KASAN_GENERIC=y. + */ +int kasan_poison_range(const void *addr, size_t size); + void __kasan_unpoison_range(const void *addr, size_t size); static __always_inline void kasan_unpoison_range(const void *addr, size_t size) { @@ -402,6 +412,7 @@ static __always_inline bool kasan_check_byte(const void *addr) #else /* CONFIG_KASAN */ +static inline int kasan_poison_range(const void *start, size_t size) { return 0; } static inline void kasan_unpoison_range(const void *address, size_t size) {} static inline void kasan_poison_pages(struct page *page, unsigned int order, bool init) {} diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index d2c70cd2afb1..7faed02264f2 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -147,6 +147,40 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init) } EXPORT_SYMBOL_GPL(kasan_poison); +int kasan_poison_range(const void *addr, size_t size) +{ + uintptr_t start_addr = (uintptr_t)addr; + uintptr_t head_granule_start; + uintptr_t poison_body_start; + uintptr_t poison_body_end; + size_t head_prefix_size; + uintptr_t end_addr; + + if ((start_addr + size) % KASAN_GRANULE_SIZE) + return -EINVAL; + + end_addr = ALIGN_DOWN(start_addr + size, KASAN_GRANULE_SIZE); + if (start_addr >= end_addr) + return -EINVAL; + + head_granule_start = ALIGN_DOWN(start_addr, KASAN_GRANULE_SIZE); + head_prefix_size = start_addr - head_granule_start; + + if (IS_ENABLED(CONFIG_KASAN_GENERIC) && head_prefix_size > 0) + kasan_poison_last_granule((void *)head_granule_start, + head_prefix_size); + + poison_body_start = ALIGN(start_addr, KASAN_GRANULE_SIZE); + poison_body_end = ALIGN_DOWN(end_addr, KASAN_GRANULE_SIZE); + + if (poison_body_start < poison_body_end) + kasan_poison((void *)poison_body_start, + poison_body_end - poison_body_start, + KASAN_SLAB_REDZONE, false); + return 0; +} +EXPORT_SYMBOL(kasan_poison_range); + #ifdef CONFIG_KASAN_GENERIC void kasan_poison_last_granule(const void *addr, size_t size) { -- 2.51.0.384.g4c02a37b29-goog