linux-kernel - [PATCH] kasan: remove vmalloc

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Message-Id: <20241022160706.38943-1-andrey.konovalov@linux.dev>
Date: Tue, 22 Oct 2024 18:07:06 +0200
From: andrey.konovalov@...ux.dev
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
	Marco Elver <elver@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	kasan-dev@...glegroups.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Samuel Holland <samuel.holland@...ive.com>,
	Sabyrzhan Tasbolatov <snovitoll@...il.com>
Subject: [PATCH] kasan: remove vmalloc_percpu test

From: Andrey Konovalov <andreyknvl@...il.com>

Commit 1a2473f0cbc0 ("kasan: improve vmalloc tests") added the
vmalloc_percpu KASAN test with the assumption that __alloc_percpu always
uses vmalloc internally, which is tagged by KASAN.

However, __alloc_percpu might allocate memory from the first per-CPU
chunk, which is not allocated via vmalloc(). As a result, the test might
fail.

Remove the test until proper KASAN annotation for the per-CPU allocated
are added; tracked in https://bugzilla.kernel.org/show_bug.cgi?id=215019.

Fixes: 1a2473f0cbc0 ("kasan: improve vmalloc tests")
Reported-by: Samuel Holland <samuel.holland@...ive.com>
Link: https://lore.kernel.org/all/4a245fff-cc46-44d1-a5f9-fd2f1c3764ae@sifive.com/
Reported-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
Link: https://lore.kernel.org/all/CACzwLxiWzNqPBp4C1VkaXZ2wDwvY3yZeetCi1TLGFipKW77drA@mail.gmail.com/
Signed-off-by: Andrey Konovalov <andreyknvl@...il.com>
---
 mm/kasan/kasan_test_c.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c
index a181e4780d9d3..d8fb281e439d5 100644
--- a/mm/kasan/kasan_test_c.c
+++ b/mm/kasan/kasan_test_c.c
@@ -1810,32 +1810,6 @@ static void vm_map_ram_tags(struct kunit *test)
 	free_pages((unsigned long)p_ptr, 1);
 }
 
-static void vmalloc_percpu(struct kunit *test)
-{
-	char __percpu *ptr;
-	int cpu;
-
-	/*
-	 * This test is specifically crafted for the software tag-based mode,
-	 * the only tag-based mode that poisons percpu mappings.
-	 */
-	KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_SW_TAGS);
-
-	ptr = __alloc_percpu(PAGE_SIZE, PAGE_SIZE);
-
-	for_each_possible_cpu(cpu) {
-		char *c_ptr = per_cpu_ptr(ptr, cpu);
-
-		KUNIT_EXPECT_GE(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_MIN);
-		KUNIT_EXPECT_LT(test, (u8)get_tag(c_ptr), (u8)KASAN_TAG_KERNEL);
-
-		/* Make sure that in-bounds accesses don't crash the kernel. */
-		*c_ptr = 0;
-	}
-
-	free_percpu(ptr);
-}
-
 /*
  * Check that the assigned pointer tag falls within the [KASAN_TAG_MIN,
  * KASAN_TAG_KERNEL) range (note: excluding the match-all tag) for tag-based
@@ -2023,7 +1997,6 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(vmalloc_oob),
 	KUNIT_CASE(vmap_tags),
 	KUNIT_CASE(vm_map_ram_tags),
-	KUNIT_CASE(vmalloc_percpu),
 	KUNIT_CASE(match_all_not_assigned),
 	KUNIT_CASE(match_all_ptr_tag),
 	KUNIT_CASE(match_all_mem_tag),
-- 
2.25.1