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Mon, 24 Aug 2020 00:10:37 -0800 Received: from MTKMBS06N2.mediatek.inc (172.21.101.130) by MTKMBS62DR.mediatek.inc (172.29.94.18) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 24 Aug 2020 01:10:34 -0700 Received: from MTKCAS06.mediatek.inc (172.21.101.30) by mtkmbs06n2.mediatek.inc (172.21.101.130) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 24 Aug 2020 16:10:34 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 24 Aug 2020 16:10:33 +0800 From: Walter Wu To: Marco Elver , Thomas Gleixner , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Matthias Brugger , John Stultz , Stephen Boyd , Andrew Morton Subject: [PATCH v2 1/6] timer: kasan: record timer stack Date: Mon, 24 Aug 2020 16:10:33 +0800 Message-ID: <20200824081033.24786-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: 378A0C9A9031AA52783956160D35589390C54B78AF36FD01C7D67ABD9CD1A3072000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200824_041046_494218_63310DBD X-CRM114-Status: GOOD ( 13.68 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Walter Wu , wsd_upstream , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org When analyze use-after-free or double-free issue, recording the timer stacks is helpful to to preserve usage history which potentially gives a hint about the affected code. Record the most recent two timer init calls in KASAN which are printed on failure in the KASAN report. For timers it has turned out to be useful to record the stack trace of the timer init call. Because if the UAF root cause is in timer init, then user can see KASAN report to get where it is registered and find out the root cause. It don't need to enable DEBUG_OBJECTS_TIMERS, but they have a chance to find out the root cause. Signed-off-by: Walter Wu Suggested-by: Marco Elver Suggested-by: Thomas Gleixner Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: John Stultz Cc: Thomas Gleixner Cc: Stephen Boyd --- v2: - Thanks for Marco and Thomas suggestion. - Remove unnecessary code and fix commit log - reuse kasan_record_aux_stack() and aux_stack to record timer and workqueue stack. --- kernel/time/timer.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index a16764b0116e..1ed8f8aca7f5 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -796,6 +796,9 @@ static void do_init_timer(struct timer_list *timer, timer->function = func; timer->flags = flags | raw_smp_processor_id(); lockdep_init_map(&timer->lockdep_map, name, key, 0); + + /* record the timer stack in order to print it in KASAN report */ + kasan_record_aux_stack(timer); } /** From patchwork Mon Aug 24 08:13:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Walter Wu X-Patchwork-Id: 11732327 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 402DE1392 for ; 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Mon, 24 Aug 2020 16:13:13 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by MTKCAS06.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 24 Aug 2020 16:13:13 +0800 From: Walter Wu To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Matthias Brugger Subject: [PATCH v2 4/6] kasan: add tests for timer stack recording Date: Mon, 24 Aug 2020 16:13:12 +0800 Message-ID: <20200824081312.24972-1-walter-zh.wu@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200824_041424_544703_98A69229 X-CRM114-Status: GOOD ( 12.94 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.0 MIME_BASE64_TEXT RAW: Message text disguised using base64 encoding -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Walter Wu , wsd_upstream , Andrey Konovalov , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+patchwork-linux-mediatek=patchwork.kernel.org@lists.infradead.org Adds a test to verify timer stack recording and print it in KASAN report. The KASAN report was as follows(cleaned up slightly): BUG: KASAN: use-after-free in kasan_timer_uaf Freed by task 0: kasan_save_stack+0x24/0x50 kasan_set_track+0x24/0x38 kasan_set_free_info+0x20/0x40 __kasan_slab_free+0x10c/0x170 kasan_slab_free+0x10/0x18 kfree+0x98/0x270 kasan_timer_function+0x1c/0x28 Last potentially related work creation: kasan_save_stack+0x24/0x50 kasan_record_tmr_stack+0xa8/0xb8 init_timer_key+0xf0/0x248 kasan_timer_uaf+0x5c/0xd8 Signed-off-by: Walter Wu Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Matthias Brugger Cc: Andrey Konovalov --- lib/test_kasan.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 6e5fb05d42d8..2bd61674c7a3 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -821,6 +821,30 @@ static noinline void __init kasan_rcu_uaf(void) call_rcu(&global_ptr->rcu, kasan_rcu_reclaim); } +static noinline void __init kasan_timer_function(struct timer_list *timer) +{ + del_timer(timer); + kfree(timer); +} + +static noinline void __init kasan_timer_uaf(void) +{ + struct timer_list *timer; + + timer = kmalloc(sizeof(struct timer_list), GFP_KERNEL); + if (!timer) { + pr_err("Allocation failed\n"); + return; + } + + timer_setup(timer, kasan_timer_function, 0); + add_timer(timer); + msleep(100); + + pr_info("use-after-free on timer\n"); + ((volatile struct timer_list *)timer)->expires; +} + static int __init kmalloc_tests_init(void) { /* @@ -869,6 +893,7 @@ static int __init kmalloc_tests_init(void) kmalloc_double_kzfree(); vmalloc_oob(); kasan_rcu_uaf(); + kasan_timer_uaf(); kasan_restore_multi_shot(multishot);