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From: andrey.konovalov@linux.dev
To: Marco Elver <elver@google.com>,
	Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	kasan-dev@googlegroups.com,
	Evgenii Stepanov <eugenis@google.com>,
	Breno Leitao <leitao@debian.org>,
	Alexander Lobakin <alobakin@pm.me>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH mm 13/21] mempool: skip slub_debug poisoning when KASAN is enabled
Date: Tue, 19 Dec 2023 23:28:57 +0100
Message-Id: <98a4b1617e8ceeb266ef9a46f5e8c7f67a563ad2.1703024586.git.andreyknvl@google.com>
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From: Andrey Konovalov <andreyknvl@google.com>

With the changes in the following patch, KASAN starts saving its metadata
within freed mempool elements.

Thus, skip slub_debug poisoning and checking of mempool elements when
KASAN is enabled. Corruptions of freed mempool elements will be detected
by KASAN anyway.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

---

Changes RFC->v1:
- This is a new patch.
---
 mm/mempool.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/mempool.c b/mm/mempool.c
index 7e1c729f292b..1fd39478c85e 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -56,6 +56,10 @@ static void __check_element(mempool_t *pool, void *element, size_t size)
 
 static void check_element(mempool_t *pool, void *element)
 {
+	/* Skip checking: KASAN might save its metadata in the element. */
+	if (kasan_enabled())
+		return;
+
 	/* Mempools backed by slab allocator */
 	if (pool->free == mempool_kfree) {
 		__check_element(pool, element, (size_t)pool->pool_data);
@@ -81,6 +85,10 @@ static void __poison_element(void *element, size_t size)
 
 static void poison_element(mempool_t *pool, void *element)
 {
+	/* Skip poisoning: KASAN might save its metadata in the element. */
+	if (kasan_enabled())
+		return;
+
 	/* Mempools backed by slab allocator */
 	if (pool->alloc == mempool_kmalloc) {
 		__poison_element(element, (size_t)pool->pool_data);
-- 
2.25.1