From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9FFF6C55ABD for ; Mon, 16 Nov 2020 09:27:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E4A6F221EB for ; Mon, 16 Nov 2020 09:27:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="AYmtyXEd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E4A6F221EB Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BF4E46B0036; Mon, 16 Nov 2020 04:27:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BA7F06B005D; Mon, 16 Nov 2020 04:27:05 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A6F236B0068; Mon, 16 Nov 2020 04:27:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 7A0216B0036 for ; Mon, 16 Nov 2020 04:27:05 -0500 (EST) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 1BE033626 for ; Mon, 16 Nov 2020 09:27:05 +0000 (UTC) X-FDA: 77489752410.26.train87_6201eb127327 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id F23901804B640 for ; Mon, 16 Nov 2020 09:27:04 +0000 (UTC) X-HE-Tag: train87_6201eb127327 X-Filterd-Recvd-Size: 9133 Received: from mail-qt1-f196.google.com (mail-qt1-f196.google.com [209.85.160.196]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Mon, 16 Nov 2020 09:27:04 +0000 (UTC) Received: by mail-qt1-f196.google.com with SMTP id g15so12364289qtq.13 for ; Mon, 16 Nov 2020 01:27:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=xO0juaBQE580WCmD+C2do+lXaG7MUpIc228ombtl2So=; b=AYmtyXEdWrp6kXBVb78bCbobLpl22LmlY+utW0OW+ZWvmj3ctCp2iAfvCycLas1hiL d6KyORZMBhYvZkJ1jLvAMtdCPvu4CNi7rw9IigvxkV306dlpusAmgkM2cl/Kv25Tlicl K2/YCP43uopQqAa8JnplZGPhC6h9001ILf/bhvEAhsi9I+GslKf/CjwTTFxjj6SZPkC+ 6nka7ZBJGOC6Mt9asBZ/GhUtEH64p6KIhLwL7Ja9MQXwDu0ZoKlBEbIAJXuZkPlMfPtg o9TH3KIJ38r+x9OrmVqfOOgpX5/ECr2jshRc52HLRlV83P4nFHzZp2QikA1OUCjuoW/4 1odA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=xO0juaBQE580WCmD+C2do+lXaG7MUpIc228ombtl2So=; b=hbQqHLJjXfPesqsPJ5MhiH9SSr0hFzQfQ9x0AABs7qBQOvt/GlUJgJ2SzAA/bt3ceV pCchhdXDByB3mEVGREbzbuxD5hZXm+CIq7Ljb8tx+OuaWdZFlVnV4Ia2y/gq9Kz1L89T t9dJ5hcmWcV7JG4iUtw9uuLQuRjvbGbFjrxmlye9Kfy8Nm61FhvZJblikyDYVEb3z+N+ pL7pZ17HaNeO4tlpKMrefXGbXt2XzcVaZldXuPWZ5Dh1WFwjdCePaG0CnRmEXb23tE/O T1Q83oett88kUclvymmtnQeKpGkmpQ2S7bO+dRcAR2YHuZvHr2hfkg43bFZlexQoWwlb OaUA== X-Gm-Message-State: AOAM531rMRnjLuXkiHV3tieRhVs0ofOiIjHI01KlO73XWzI+LqznBwJ/ OYjCp2PXWGUIMjAkBUMIt+WRgC8vvlIZvbcv75homA== X-Google-Smtp-Source: ABdhPJyOnYx143blG3oTAJfoG1SkneonElF+InYoaKB3gm9FknORy0i0cO0JvZ+xkKiMt/Ri89Nio4h0t1Uyle7xRqc= X-Received: by 2002:ac8:37f2:: with SMTP id e47mr13349765qtc.290.1605518823487; Mon, 16 Nov 2020 01:27:03 -0800 (PST) MIME-Version: 1.0 References: <1605508168-7418-1-git-send-email-Kuan-Ying.Lee@mediatek.com> <1605508168-7418-2-git-send-email-Kuan-Ying.Lee@mediatek.com> In-Reply-To: <1605508168-7418-2-git-send-email-Kuan-Ying.Lee@mediatek.com> From: Dmitry Vyukov Date: Mon, 16 Nov 2020 10:26:52 +0100 Message-ID: Subject: Re: [PATCH v2 1/1] kasan: fix object remain in offline per-cpu quarantine To: Kuan-Ying Lee Cc: Andrey Ryabinin , Alexander Potapenko , Andrew Morton , Matthias Brugger , kasan-dev , Linux-MM , LKML , Linux ARM , linux-mediatek@lists.infradead.org, nicholas.tang@mediatek.com, Miles Chen , guangye.yang@mediatek.com, wsd_upstream Content-Type: text/plain; charset="UTF-8" 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: On Mon, Nov 16, 2020 at 7:30 AM Kuan-Ying Lee wrote: > > 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); Looks much nicer now! What is the story with interrupts in these callbacks? In the previous patch you mentioned that this CPU can still receive interrupts for a brief period of time. If these interrupts also free something, can't we corrupt the per-cpu quarantine? In quarantine_put we protect it by disabling interrupts I think. > + 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); > -- > 2.18.0