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Mon, 16 Nov 2020 14:30:08 +0800 From: Kuan-Ying Lee To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Andrew Morton , Matthias Brugger Subject: [PATCH v2 1/1] kasan: fix object remain in offline per-cpu quarantine Date: Mon, 16 Nov 2020 14:29:28 +0800 Message-ID: <1605508168-7418-2-git-send-email-Kuan-Ying.Lee@mediatek.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1605508168-7418-1-git-send-email-Kuan-Ying.Lee@mediatek.com> References: <1605508168-7418-1-git-send-email-Kuan-Ying.Lee@mediatek.com> MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201116_013047_905204_37435DEB X-CRM114-Status: GOOD ( 17.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: miles.chen@mediatek.com, wsd_upstream@mediatek.com, Kuan-Ying Lee , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, nicholas.tang@mediatek.com, linux-mediatek@lists.infradead.org, guangye.yang@mediatek.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org We hit this issue in our internal test. When enabling generic kasan, a kfree()'d object is put into per-cpu quarantine first. If the cpu goes offline, object still remains in the per-cpu quarantine. If we call kmem_cache_destroy() now, slub will report "Objects remaining" error. [ 74.982625] ============================================================================= [ 74.983380] BUG test_module_slab (Not tainted): Objects remaining in test_module_slab on __kmem_cache_shutdown() [ 74.984145] ----------------------------------------------------------------------------- [ 74.984145] [ 74.984883] Disabling lock debugging due to kernel taint [ 74.985561] INFO: Slab 0x(____ptrval____) objects=34 used=1 fp=0x(____ptrval____) flags=0x2ffff00000010200 [ 74.986638] CPU: 3 PID: 176 Comm: cat Tainted: G B 5.10.0-rc1-00007-g4525c8781ec0-dirty #10 [ 74.987262] Hardware name: linux,dummy-virt (DT) [ 74.987606] Call trace: [ 74.987924] dump_backtrace+0x0/0x2b0 [ 74.988296] show_stack+0x18/0x68 [ 74.988698] dump_stack+0xfc/0x168 [ 74.989030] slab_err+0xac/0xd4 [ 74.989346] __kmem_cache_shutdown+0x1e4/0x3c8 [ 74.989779] kmem_cache_destroy+0x68/0x130 [ 74.990176] test_version_show+0x84/0xf0 [ 74.990679] module_attr_show+0x40/0x60 [ 74.991218] sysfs_kf_seq_show+0x128/0x1c0 [ 74.991656] kernfs_seq_show+0xa0/0xb8 [ 74.992059] seq_read+0x1f0/0x7e8 [ 74.992415] kernfs_fop_read+0x70/0x338 [ 74.993051] vfs_read+0xe4/0x250 [ 74.993498] ksys_read+0xc8/0x180 [ 74.993825] __arm64_sys_read+0x44/0x58 [ 74.994203] el0_svc_common.constprop.0+0xac/0x228 [ 74.994708] do_el0_svc+0x38/0xa0 [ 74.995088] el0_sync_handler+0x170/0x178 [ 74.995497] el0_sync+0x174/0x180 [ 74.996050] INFO: Object 0x(____ptrval____) @offset=15848 [ 74.996752] INFO: Allocated in test_version_show+0x98/0xf0 age=8188 cpu=6 pid=172 [ 75.000802] stack_trace_save+0x9c/0xd0 [ 75.002420] set_track+0x64/0xf0 [ 75.002770] alloc_debug_processing+0x104/0x1a0 [ 75.003171] ___slab_alloc+0x628/0x648 [ 75.004213] __slab_alloc.isra.0+0x2c/0x58 [ 75.004757] kmem_cache_alloc+0x560/0x588 [ 75.005376] test_version_show+0x98/0xf0 [ 75.005756] module_attr_show+0x40/0x60 [ 75.007035] sysfs_kf_seq_show+0x128/0x1c0 [ 75.007433] kernfs_seq_show+0xa0/0xb8 [ 75.007800] seq_read+0x1f0/0x7e8 [ 75.008128] kernfs_fop_read+0x70/0x338 [ 75.008507] vfs_read+0xe4/0x250 [ 75.008990] ksys_read+0xc8/0x180 [ 75.009462] __arm64_sys_read+0x44/0x58 [ 75.010085] el0_svc_common.constprop.0+0xac/0x228 [ 75.011006] kmem_cache_destroy test_module_slab: Slab cache still has objects Register a cpu hotplug function to remove all objects in the offline per-cpu quarantine when cpu is going offline. Set a per-cpu variable to indicate this cpu is offline. Signed-off-by: Kuan-Ying Lee Suggested-by: Dmitry Vyukov Reported-by: Guangye Yang Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrew Morton Cc: Matthias Brugger --- mm/kasan/quarantine.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c index 4c5375810449..16e618ea805e 100644 --- a/mm/kasan/quarantine.c +++ b/mm/kasan/quarantine.c @@ -29,6 +29,7 @@ #include #include #include +#include #include "../slab.h" #include "kasan.h" @@ -43,6 +44,7 @@ struct qlist_head { struct qlist_node *head; struct qlist_node *tail; size_t bytes; + bool offline; }; #define QLIST_INIT { NULL, NULL, 0 } @@ -188,6 +190,11 @@ void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) local_irq_save(flags); q = this_cpu_ptr(&cpu_quarantine); + if (q->offline) { + qlink_free(&info->quarantine_link, cache); + local_irq_restore(flags); + return; + } qlist_put(q, &info->quarantine_link, cache->size); if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) { qlist_move_all(q, &temp); @@ -328,3 +335,31 @@ void quarantine_remove_cache(struct kmem_cache *cache) synchronize_srcu(&remove_cache_srcu); } + +static int kasan_cpu_online(unsigned int cpu) +{ + this_cpu_ptr(&cpu_quarantine)->offline = false; + return 0; +} + +static int kasan_cpu_offline(unsigned int cpu) +{ + struct qlist_head *q; + + q = this_cpu_ptr(&cpu_quarantine); + q->offline = true; + qlist_free_all(q, NULL); + return 0; +} + +static int __init kasan_cpu_offline_quarantine_init(void) +{ + int ret = 0; + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mm/kasan:online", + kasan_cpu_online, kasan_cpu_offline); + if (ret < 0) + pr_err("kasan offline cpu quarantine register failed [%d]\n", ret); + return ret; +} +late_initcall(kasan_cpu_offline_quarantine_init);