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[2620:137:e000::1:20]) by mx.google.com with ESMTP id p15-20020aa79e8f000000b005a904cbf3fbsi2538712pfq.219.2023.03.03.08.24.12; Fri, 03 Mar 2023 08:24:25 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=jZFs3UtZ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230282AbjCCQTq (ORCPT + 99 others); Fri, 3 Mar 2023 11:19:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229959AbjCCQTo (ORCPT ); Fri, 3 Mar 2023 11:19:44 -0500 Received: from mail-qt1-x833.google.com (mail-qt1-x833.google.com [IPv6:2607:f8b0:4864:20::833]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D569214235 for ; Fri, 3 Mar 2023 08:19:29 -0800 (PST) Received: by mail-qt1-x833.google.com with SMTP id l13so3418385qtv.3 for ; Fri, 03 Mar 2023 08:19:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1677860369; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=e+yLYCDzltm9gpZbxWXVl1NxY3BGRavECq9TKfztIfw=; b=jZFs3UtZTl3mfc6RFNt3+tEnShBIQ5UdZ9VE9cp5VhTWobN/f/yxnc9ugydM2sUpun tsiSjacoBnMcbmkLu4LizCPNoce2k1BZnnVewxiNUTdLS1uD/sWE1DmLiz7J9L0Loe6R nF2Zt4oiGDvRrefObXq/aE6xzrt03IAwFbyUgbhaNLhCfComOuvyHwd6LcOHwoaLCzDz PvY5+wTvdKYGmmJVjdDFuFEIweqzIkub+43t/rVPHi66lLTentwcwQntswnuSOQUZ//t YAeBDw2LAnAhUB01jZ9PcbDDRKstETEqD5yAn2P0AHPfyqipBZnXIodwOD4qU8A5CDJ0 P8Mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1677860369; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=e+yLYCDzltm9gpZbxWXVl1NxY3BGRavECq9TKfztIfw=; b=KRz53FSVLpGHM78oMqJru5s4X/7xRdJtg1umjEmPOpyzXhAcpzNNisxLpzqP4/sBwO +LC/0LVJk15GfIU2jgkF9RNwLFYDmC6/I2E6UUd2cm9fxz1psTUu0PgffsYfV6CSWyuC YPcnQI7wy0g4BeUG+t0DglR5cr2HKZwaGK98Hpyv5P/YJiXgcGZZ9zmJUjozagewhMTU Y9bhhsuUCbOpDKmtqWWi9wsErLuSAEsUEbUd0TNw2++5k9u8P/PpGgwWuDHc6H1YY2ft oiRAsa5g7M1EUQ71SMgbb/uS4Nonyen789izHPw6kMJEJBTsThE+x4TzvQAltKdQpKdd +0Tw== X-Gm-Message-State: AO0yUKVBXJd8tKdu1Opry916IAth2YPIPPBSZJXm8Vc4NImoruuqcI2S J8tV64Y6c5cFLDWh2SxayUo= X-Received: by 2002:ac8:5a49:0:b0:3b2:4309:99e with SMTP id o9-20020ac85a49000000b003b24309099emr4416494qta.54.1677860368886; Fri, 03 Mar 2023 08:19:28 -0800 (PST) Received: from ArchLinux.lan ([68.74.118.125]) by smtp.gmail.com with ESMTPSA id 4-20020a370304000000b0073bb00eb0besm2039913qkd.22.2023.03.03.08.19.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Mar 2023 08:19:28 -0800 (PST) From: Schspa Shi To: tglx@linutronix.de, longman@redhat.com, swboyd@chromium.org, linux@roeck-us.net, wuchi.zero@gmail.com Cc: linux-kernel@vger.kernel.org, Schspa Shi , syzbot+5093ba19745994288b53@syzkaller.appspotmail.com Subject: [PATCH 1/2] debugobject: fix concurrency issues with is_static_object Date: Sat, 4 Mar 2023 00:19:05 +0800 Message-Id: <20230303161906.831686-1-schspa@gmail.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-Spam-Status: No, score=1.2 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Level: * X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1759364425142646439?= X-GMAIL-MSGID: =?utf-8?q?1759364425142646439?= The is_static_object implementation relay on the initial state of the object. If multiple places are accessed concurrently, there is a probability that the debug object has been registered in the system, which will invalidate the judgment of is_static_object. The following is the scenario where the problem occurs: T0 T1 ========================================================================= mod_timer(); debug_object_assert_init db = get_bucket((unsigned long) addr); raw_spin_lock_irqsave(&db->lock, flags); obj = lookup_object(addr, db); if (!obj) { raw_spin_unlock_irqrestore(&db->lock, flags); << Context switch >> mod_timer(); debug_object_assert_init ... enqueue_timer(); /* * The initial state changed a static timer object, and * is_static_object will return false */ if (descr->is_static_object && descr->is_static_object(addr)) { debug_object_init(); } else { << Hit here for a static object >> debug_print_object(&o, "assert_init"); debug_object_fixup(descr->fixup_assert_init, addr, ODEBUG_STATE_NOTAVAILABLE); } } To fix it, we got the is_static_object called within db->lock, and save it's state to struct debug_obj. This will ensure we won't hit the code branch not belong to the static object. For the same static object, debug_object_init may enter multiple times, but there is a lock in debug_object_init to ensure that there is no problem. Reported-by: syzbot+5093ba19745994288b53@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=22c8a5938eab640d1c6bcc0e3dc7be519d878462 Signed-off-by: Schspa Shi --- include/linux/debugobjects.h | 1 + lib/debugobjects.c | 71 ++++++++++++++++++++++++++++-------- 2 files changed, 56 insertions(+), 16 deletions(-) diff --git a/include/linux/debugobjects.h b/include/linux/debugobjects.h index 32444686b6ff4..544a6111b97f6 100644 --- a/include/linux/debugobjects.h +++ b/include/linux/debugobjects.h @@ -30,6 +30,7 @@ struct debug_obj { enum debug_obj_state state; unsigned int astate; void *object; + bool is_static; const struct debug_obj_descr *descr; }; diff --git a/lib/debugobjects.c b/lib/debugobjects.c index df86e649d8be0..d1be18158a1f7 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -275,6 +275,8 @@ alloc_object(void *addr, struct debug_bucket *b, const struct debug_obj_descr *d obj->descr = descr; obj->state = ODEBUG_STATE_NONE; obj->astate = 0; + obj->is_static = descr->is_static_object && + descr->is_static_object(addr); hlist_add_head(&obj->node, &b->list); } return obj; @@ -581,7 +583,16 @@ __debug_object_init(void *addr, const struct debug_obj_descr *descr, int onstack debug_objects_oom(); return; } + check_stack = true; + } else { + /* + * The debug object is inited, and we should check this again + */ + if (obj->is_static) { + raw_spin_unlock_irqrestore(&db->lock, flags); + return; + } } switch (obj->state) { @@ -640,6 +651,29 @@ void debug_object_init_on_stack(void *addr, const struct debug_obj_descr *descr) } EXPORT_SYMBOL_GPL(debug_object_init_on_stack); +/* + * Check static object. + */ +static bool debug_object_check_static(struct debug_bucket *db, void *addr, + const struct debug_obj_descr *descr) +{ + struct debug_obj *obj; + + /* + * The is_static_object implementation relay on the initial state of the + * object. If multiple places are accessed concurrently, there is a + * probability that the debug object has been registered in the system, + * which will invalidate the judgment of is_static_object. + */ + lockdep_assert_held(&db->lock); + + obj = lookup_object(addr, db); + if (likely(obj)) + return obj->is_static; + + return descr->is_static_object && descr->is_static_object(addr); +} + /** * debug_object_activate - debug checks when an object is activated * @addr: address of the object @@ -656,6 +690,7 @@ int debug_object_activate(void *addr, const struct debug_obj_descr *descr) struct debug_obj o = { .object = addr, .state = ODEBUG_STATE_NOTAVAILABLE, .descr = descr }; + bool is_static; if (!debug_objects_enabled) return 0; @@ -696,6 +731,7 @@ int debug_object_activate(void *addr, const struct debug_obj_descr *descr) return ret; } + is_static = debug_object_check_static(db, addr, descr); raw_spin_unlock_irqrestore(&db->lock, flags); /* @@ -705,7 +741,7 @@ int debug_object_activate(void *addr, const struct debug_obj_descr *descr) * static object is tracked in the object tracker. If * not, this must be a bug, so we try to fix it up. */ - if (descr->is_static_object && descr->is_static_object(addr)) { + if (is_static) { /* track this static object */ debug_object_init(addr, descr); debug_object_activate(addr, descr); @@ -872,6 +908,7 @@ void debug_object_assert_init(void *addr, const struct debug_obj_descr *descr) struct debug_bucket *db; struct debug_obj *obj; unsigned long flags; + bool is_static; if (!debug_objects_enabled) return; @@ -886,13 +923,14 @@ void debug_object_assert_init(void *addr, const struct debug_obj_descr *descr) .state = ODEBUG_STATE_NOTAVAILABLE, .descr = descr }; + is_static = debug_object_check_static(db, addr, descr); raw_spin_unlock_irqrestore(&db->lock, flags); /* * Maybe the object is static, and we let the type specific * code confirm. Track this static object if true, else invoke * fixup. */ - if (descr->is_static_object && descr->is_static_object(addr)) { + if (is_static) { /* Track this static object */ debug_object_init(addr, descr); } else { @@ -1215,7 +1253,8 @@ static __initconst const struct debug_obj_descr descr_type_test = { .fixup_free = fixup_free, }; -static __initdata struct self_test obj = { .static_init = 0 }; +static struct self_test obj __initdata = { .static_init = 0 }; +static struct self_test sobj __initdata = { .static_init = 1 }; static void __init debug_objects_selftest(void) { @@ -1256,26 +1295,26 @@ static void __init debug_objects_selftest(void) if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings)) goto out; - obj.static_init = 1; - debug_object_activate(&obj, &descr_type_test); - if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings)) + debug_object_init(&sobj, &descr_type_test); + debug_object_activate(&sobj, &descr_type_test); + if (check_results(&sobj, ODEBUG_STATE_ACTIVE, fixups, warnings)) goto out; - debug_object_init(&obj, &descr_type_test); - if (check_results(&obj, ODEBUG_STATE_INIT, ++fixups, ++warnings)) + debug_object_init(&sobj, &descr_type_test); + if (check_results(&sobj, ODEBUG_STATE_INIT, ++fixups, ++warnings)) goto out; - debug_object_free(&obj, &descr_type_test); - if (check_results(&obj, ODEBUG_STATE_NONE, fixups, warnings)) + debug_object_free(&sobj, &descr_type_test); + if (check_results(&sobj, ODEBUG_STATE_NONE, fixups, warnings)) goto out; #ifdef CONFIG_DEBUG_OBJECTS_FREE - debug_object_init(&obj, &descr_type_test); - if (check_results(&obj, ODEBUG_STATE_INIT, fixups, warnings)) + debug_object_init(&sobj, &descr_type_test); + if (check_results(&sobj, ODEBUG_STATE_INIT, fixups, warnings)) goto out; - debug_object_activate(&obj, &descr_type_test); - if (check_results(&obj, ODEBUG_STATE_ACTIVE, fixups, warnings)) + debug_object_activate(&sobj, &descr_type_test); + if (check_results(&sobj, ODEBUG_STATE_ACTIVE, fixups, warnings)) goto out; - __debug_check_no_obj_freed(&obj, sizeof(obj)); - if (check_results(&obj, ODEBUG_STATE_NONE, ++fixups, ++warnings)) + __debug_check_no_obj_freed(&sobj, sizeof(sobj)); + if (check_results(&sobj, ODEBUG_STATE_NONE, ++fixups, ++warnings)) goto out; #endif pr_info("selftest passed\n"); From patchwork Fri Mar 3 16:19:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Schspa Shi X-Patchwork-Id: 63984 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:5915:0:0:0:0:0 with SMTP id v21csp500543wrd; Fri, 3 Mar 2023 08:23:19 -0800 (PST) X-Google-Smtp-Source: AK7set9V2PxjQ9L8tNxp2TfhmzJEG4AKXFNxuvoexqJaJT2CbyFDVSfgPM+RUuSVaVfEBW2QBO1a X-Received: by 2002:a17:906:af8d:b0:8a6:df80:7bbe with SMTP id mj13-20020a170906af8d00b008a6df807bbemr2217209ejb.49.1677860599802; Fri, 03 Mar 2023 08:23:19 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1677860599; cv=none; d=google.com; s=arc-20160816; b=kHzqzOrhxF+fn5c7pO5QU7eNHdTfiIjwdbmVuEfex1YG4wukelXVNxj8t9x6flL8ra lxsSpA+QX2hMcdr7jE5Yvt7SB+9MjlEiOzR+90fXKr3s5hOTsfAvj3i+O3XccyyvfIWP J23DduVIJxeJG+Ixa0P7DSaSSnvq8PqZcc2pVOqaYO3mH+2QYd5BHXZor4lWuv19DM6s NXIuKWJFpRacXLZrhScJ3gTAg+YUsFEK0IFKUewEXk8qk3GEzNhMkiO58pUi8qvVdltb CPx0SmgYIQP5vsYWwyPFRdFIHlwtKIY1qsbEeXoayUSUluRPoZVpyFkCdllwO+IltTy3 70iw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=Lj/t6Fz/u75jqRo8OM20KwqRZGxc+UX5ZSqckuG+0gc=; b=JqGvJncMLeUV1uU9pEKrlAxifzrXSQ0pBdVIGm30ULvUr586lsRNbg74L4/b8fuNEY t+pqqBgmT+aOC8WetXnMEdJkNBhYSRn2BV0jOeXJVG0CtwmIX+MDY1NARr2AvsWur+Ex wMToCVC1v3MhecmhKLHuPcGeG3bI03zHLkfIowwiSqlHtknjHb3ilGC9onu6nPH4YvHd k941ZgZOPWyI1QmtlnSuGIWOCJ3D3XA2DM6WU2NDWZ50rG8V7cv+f8IvGF0EcCi8faUM ry1/tebR24YJj20MmOGJVfZ5le1vCo8MUa7XHT9uxx/Janaxu980PoU4W6pMwJnlmmsr 1MlQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=VsT7ikp3; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from out1.vger.email (out1.vger.email. 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Tested on little-endian arm64 qemu, result: [ 2.385735] KTAP version 1 [ 2.385860] 1..1 [ 2.386406] KTAP version 1 [ 2.386658] # Subtest: static debugobject init [ 2.386726] 1..1 [ 2.401777] ok 1 static_debugobject_test [ 2.402455] ok 1 static debugobject init Signed-off-by: Schspa Shi --- MAINTAINERS | 5 ++ lib/Kconfig.debug | 14 ++++ lib/Makefile | 2 + lib/test_static_debug_object.c | 125 +++++++++++++++++++++++++++++++++ 4 files changed, 146 insertions(+) create mode 100644 lib/test_static_debug_object.c diff --git a/MAINTAINERS b/MAINTAINERS index b0db911207ba4..38187e2921691 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -23202,6 +23202,11 @@ L: linux-mm@kvack.org S: Maintained F: mm/zswap.c +STATIC DEBUGOBJECT TEST +M: Schspa Shi +S: Maintained +F: lib/test_static_debug_object.c + THE REST M: Linus Torvalds L: linux-kernel@vger.kernel.org diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c8b379e2e9adc..9d5ee631d4380 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2801,6 +2801,20 @@ config TEST_CLOCKSOURCE_WATCHDOG If unsure, say N. +config TEST_STATIC_DEBUGOBJECT + tristate "KUnit test for static debugobject" + depends on KUNIT + select KPROBES + select DEBUG_OBJECTS + select DEBUG_OBJECTS_TIMERS + help + This builds the static debugobject unit test, which runs on boot. + Tests the static debug object correctness. + For more information on KUnit and unit tests in general please refer + to the KUnit documentation in Documentation/dev-tools/kunit/. + + If unsure, say N. + endif # RUNTIME_TESTING_MENU config ARCH_USE_MEMTEST diff --git a/lib/Makefile b/lib/Makefile index baf2821f7a00f..f663686beabd9 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -427,3 +427,5 @@ $(obj)/$(TEST_FORTIFY_LOG): $(addprefix $(obj)/, $(TEST_FORTIFY_LOGS)) FORCE ifeq ($(CONFIG_FORTIFY_SOURCE),y) $(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG) endif + +obj-$(CONFIG_TEST_STATIC_DEBUGOBJECT) += test_static_debug_object.o diff --git a/lib/test_static_debug_object.c b/lib/test_static_debug_object.c new file mode 100644 index 0000000000000..8a0d6ab5c24b5 --- /dev/null +++ b/lib/test_static_debug_object.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * THis module tests the static debugobject via a static timer instance. This + * test use kretprobe to inject some delay to make the problem easier to + * reproduce. + * + * Copyright (c) 2023, Schspa Shi + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void ktest_timer_func(struct timer_list *); + +static DEFINE_TIMER(ktest_timer, ktest_timer_func); +static int timer_stop; +DEFINE_SPINLOCK(tlock); + +static DEFINE_PER_CPU(struct work_struct, timer_debugobject_test_work); + +static void timer_debugobject_workfn(struct work_struct *work) +{ + mod_timer(&ktest_timer, jiffies + (5 * HZ)); +} + +/* + * Reaper for links from keyrings to dead keys. + */ +static void ktest_timer_func(struct timer_list *t) +{ + unsigned long flags; + + spin_lock_irqsave(&tlock, flags); + if (!timer_stop) + mod_timer(&ktest_timer, jiffies + (1 * HZ)); + spin_unlock_irqrestore(&tlock, flags); +} + + +static int static_object_check_handler( + struct kretprobe_instance *ri, struct pt_regs *regs) +{ + void *address; + + address = (void *)regs_get_register(regs, 0); + + if (address == &ktest_timer) { + int this_cpu = raw_smp_processor_id(); + /* + * This hook point adds an extra delay to make the problem + * easier to reproduce. We need different delay for + * differenct processor. + */ + mdelay(this_cpu * 100); + } + + return 0; +} + + +static struct kretprobe is_static_kretprobes = { + .entry_handler = static_object_check_handler, + .data_size = 0, + /* Probe up to 512 instances concurrently. */ + .maxactive = 512, + .kp = { + .symbol_name = "timer_is_static_object", + } +}; + + +static void static_debugobject_test(struct kunit *test) +{ + unsigned long flags; + int cpu; + int ret; + + ret = register_kretprobe(&is_static_kretprobes); + KUNIT_ASSERT_EQ(test, ret, 0); + + /* Do test */ + cpus_read_lock(); + for_each_online_cpu(cpu) { + struct work_struct *work = + &per_cpu(timer_debugobject_test_work, cpu); + INIT_WORK(work, timer_debugobject_workfn); + schedule_work_on(cpu, work); + } + + for_each_online_cpu(cpu) { + struct work_struct *work = + &per_cpu(timer_debugobject_test_work, cpu); + flush_work(work); + } + cpus_read_unlock(); + + spin_lock_irqsave(&tlock, flags); + timer_stop = 0; + spin_unlock_irqrestore(&tlock, flags); + + del_timer_sync(&ktest_timer); + + unregister_kretprobe(&is_static_kretprobes); +} + +static struct kunit_case static_debugobject_init_cases[] = { + KUNIT_CASE(static_debugobject_test), + {} +}; + +static struct kunit_suite static_debugobject_suite = { + .name = "static debugobject init", + .test_cases = static_debugobject_init_cases, +}; + +kunit_test_suite(static_debugobject_suite); +MODULE_AUTHOR("Schspa "); +MODULE_LICENSE("GPL");