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Tue, 29 Jul 2025 16:14:12 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 29nsJ1TziGg5WQAAD6G6ig (envelope-from ); Tue, 29 Jul 2025 16:14:12 +0000 Message-ID: <6aeb9c5d-7c3f-4c0c-989f-df309267ffbe@suse.cz> Date: Tue, 29 Jul 2025 18:14:12 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] kasan: add test for SLAB_TYPESAFE_BY_RCU quarantine skipping Content-Language: en-US To: Jann Horn , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Andrew Morton Cc: kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250728-kasan-tsbrcu-noquarantine-test-v1-1-fa24d9ab7f41@google.com> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: <20250728-kasan-tsbrcu-noquarantine-test-v1-1-fa24d9ab7f41@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Level: X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FREEMAIL_TO(0.00)[google.com,gmail.com,arm.com,linux-foundation.org]; TAGGED_RCPT(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCPT_COUNT_SEVEN(0.00)[10]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.cz:mid] X-Spam-Flag: NO X-Spam-Score: -2.80 On 7/28/25 17:25, Jann Horn wrote: > Verify that KASAN does not quarantine objects in SLAB_TYPESAFE_BY_RCU slabs > if CONFIG_SLUB_RCU_DEBUG is off. > > Suggested-by: Andrey Konovalov > Signed-off-by: Jann Horn > --- > Feel free to either take this as a separate commit or squash it into the > preceding "[PATCH] kasan: skip quarantine if object is still accessible > under RCU". > > I tested this by running KASAN kunit tests for x86-64 with KASAN > and tracing manually enabled; there are two failing tests but those > seem unrelated (kasan_memchr is unexpectedly not detecting some > accesses, and kasan_strings is also failing). > --- > mm/kasan/kasan_test_c.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c > index 5f922dd38ffa..15d3d82041bf 100644 > --- a/mm/kasan/kasan_test_c.c > +++ b/mm/kasan/kasan_test_c.c > @@ -1073,6 +1073,41 @@ static void kmem_cache_rcu_uaf(struct kunit *test) > kmem_cache_destroy(cache); > } > > +/* > + * Check that SLAB_TYPESAFE_BY_RCU objects are immediately reused when > + * CONFIG_SLUB_RCU_DEBUG is off, and stay at the same address. > + */ > +static void kmem_cache_rcu_reuse(struct kunit *test) > +{ > + char *p, *p2; > + struct kmem_cache *cache; > + > + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_SLUB_RCU_DEBUG); > + > + cache = kmem_cache_create("test_cache", 16, 0, SLAB_TYPESAFE_BY_RCU, > + NULL); > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); Hmm is there anything inherent in kunit that keeps the test pinned to the same cpu? Otherwise I think you'll need here migrate_disable(); > + p = kmem_cache_alloc(cache, GFP_KERNEL); > + if (!p) { > + kunit_err(test, "Allocation failed: %s\n", __func__); > + kmem_cache_destroy(cache); > + return; > + } > + > + kmem_cache_free(cache, p); > + p2 = kmem_cache_alloc(cache, GFP_KERNEL); and here (or later) migrate_enable(); > + if (!p2) { > + kunit_err(test, "Allocation failed: %s\n", __func__); > + kmem_cache_destroy(cache); > + return; > + } > + KUNIT_ASSERT_PTR_EQ(test, p, p2); Otherwise the cpu slab caching of SLUB and a migration could mean this won't hold as you'll get object from another slab. > + kmem_cache_free(cache, p2); > + kmem_cache_destroy(cache); > +} > + > static void kmem_cache_double_destroy(struct kunit *test) > { > struct kmem_cache *cache; > @@ -2098,6 +2133,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { > KUNIT_CASE(kmem_cache_double_free), > KUNIT_CASE(kmem_cache_invalid_free), > KUNIT_CASE(kmem_cache_rcu_uaf), > + KUNIT_CASE(kmem_cache_rcu_reuse), > KUNIT_CASE(kmem_cache_double_destroy), > KUNIT_CASE(kmem_cache_accounted), > KUNIT_CASE(kmem_cache_bulk), > > --- > base-commit: 0df7d6c9705b283d5b71ee0ae86ead05bd3a55a9 > change-id: 20250728-kasan-tsbrcu-noquarantine-test-5c723367e056 > prerequisite-change-id: 20250723-kasan-tsbrcu-noquarantine-e207bb990e24:v1 > prerequisite-patch-id: 4fab9d3a121bfcaacc32a40f606b7c04e0c6fdd0 >