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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 2D076C48BC2 for ; Sun, 27 Jun 2021 09:27:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F391E61C32 for ; Sun, 27 Jun 2021 09:27:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230094AbhF0J3l (ORCPT ); Sun, 27 Jun 2021 05:29:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229534AbhF0J3f (ORCPT ); Sun, 27 Jun 2021 05:29:35 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A13F5C061574 for ; Sun, 27 Jun 2021 02:27:10 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id b5-20020a17090a9905b029016fc06f6c5bso8351748pjp.5 for ; Sun, 27 Jun 2021 02:27:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=rWCDYW209iwqGBaTcBu1cWNJOi/oleQfwRCVNcyXwRs=; b=ho+BYmsdeIGTq/y3Pdh+cFWW2Z/0rnk5GafoPQu/TEKHXVDDmr88GidoFg6Mm/3KGe IQ5dD9LGdyo3gQWVXhk11l729thUFWT2yVg9WvMsPACkQ0LuQXfCUmMheMhtBJJG8nlE IuqEWw5esiCEMvdnwT4hZe5Kxr77pNmMCYX+CueLZOuNrKPAzJSxYGel7kdO9upLrfXG 9rDMIgyTkK5ydyRL8Pmxp2Daz0I4jLkBWBtOVJygUkyP7zO70MJy347kTvgYlninvoEq Md50iLYYuEFnc4kerNwqxmm+H4+zLIlG8fHsUVuBLEK9yqenaFGxwCFb58CA4GbY9EFE 3peA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=rWCDYW209iwqGBaTcBu1cWNJOi/oleQfwRCVNcyXwRs=; b=RCJamdXkljuGmX5FHy259OKdQEJp7q98PKRfXwXDVwIEBCC0wWu9HRaya5nugD5jYB zFiiesaOwIMBkaowXgQE5q+t+Qhq/fsddWK5s/JhTau1l3xb153BCTwCYKEE39x7WgD3 c4FzNJ++/UXmYPGpErs/3/aaLdsTvJ0uN4Sat7ySA/xrVB9HUDgK6B0KbU7gTRHQjA1r rkjNLMVlxLn7JT4tBHqlRpjE69tgFeVzks6w0mttl64S8bpWk50+KFNvNehRXgNal7OA 38B0+Kpjxf5UwyRH+6gdkb/KBdC52MugXDod37EiSDvHc4A/VqrP0wYu6siV6oI6oPqg EsRg== X-Gm-Message-State: AOAM533jwwUqpz/7ve2ivRgIwZ0M9iqfP5k2BQRbMvKg8QO2s1Ew7ffB 1XJvLqshb7MmE97A0M7aMOXv4Xf4gZw= X-Google-Smtp-Source: ABdhPJyq2suc/QqEbkIurkgn5OlzC2b9olqRGaNuGsLiX3F5EJWJjot5YZQRaQ6X9G6GSio1oIEs7A== X-Received: by 2002:a17:902:7c94:b029:fc:5e8b:e645 with SMTP id y20-20020a1709027c94b02900fc5e8be645mr17333678pll.18.1624786029965; Sun, 27 Jun 2021 02:27:09 -0700 (PDT) Received: from WRT-WX9.. ([141.164.41.4]) by smtp.gmail.com with ESMTPSA id u20sm10756398pfn.189.2021.06.27.02.27.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Jun 2021 02:27:09 -0700 (PDT) From: Changbin Du To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Changbin Du Subject: [PATCH] riscv: stacktrace: fix dump_backtrace/walk_stackframe with NULL task Date: Sun, 27 Jun 2021 17:26:59 +0800 Message-Id: <20210627092659.46193-1-changbin.du@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Some places try to show backtrace with NULL task, and expect the task is 'current'. For example, dump_stack()->show_stack(NULL,...). So the stacktrace code should take care of this case. Here is an oops caused by this issue when accessing the NULL task. [ 15.180813] Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance. [ 15.182382] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc7-00111-g625acffd7ae2-dirty #18 [ 15.183431] Hardware name: riscv-virtio,qemu (DT) [ 15.184253] Call Trace: [ 15.223617] Unable to handle kernel paging request at virtual address 0000000000001590 [ 15.267378] Oops [#1] [ 15.268215] Modules linked in: [ 15.272027] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc7-00111-g625acffd7ae2-dirty #18 [ 15.273997] Hardware name: riscv-virtio,qemu (DT) [ 15.275134] epc : walk_stackframe+0xc4/0xdc [ 15.280146] ra : dump_backtrace+0x30/0x38 [ 15.280799] epc : ffffffff8000597e ra : ffffffff800059c6 sp : ffffffe002383d60 [ 15.281622] gp : ffffffff8179ad18 tp : ffffffe002378000 t0 : ffffffff81bc1a3f [ 15.282574] t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffffe002383dc0 [ 15.283782] s1 : ffffffff812b7d18 a0 : 0000000000001000 a1 : 0000000000000000 [ 15.285115] a2 : ffffffff807ec668 a3 : ffffffff812b7d18 a4 : c76c00cabf08b500 [ 15.286213] a5 : 0000000000001000 a6 : 000000001a9ef260 a7 : 0000000000000000 [ 15.287317] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000 [ 15.288323] s5 : ffffffff807ec668 s6 : ffffffff812b7d18 s7 : 0000000000000000 [ 15.289530] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000000000000000 [ 15.290995] s11: 0000000000000000 t3 : 0000000000000001 t4 : 0000000000000000 [ 15.292465] t5 : 206f74206e6f6974 t6 : ffffffe002383b28 [ 15.293859] status: 0000000000000100 badaddr: 0000000000001590 cause: 000000000000000d [ 15.296035] [] walk_stackframe+0xc4/0xdc [ 15.297342] [] dump_backtrace+0x30/0x38 [ 15.298333] [] show_stack+0x40/0x4c [ 15.299765] [] dump_stack+0x7c/0x96 [ 15.300553] [] panic+0x118/0x300 [ 15.301147] [] kernel_init+0x12c/0x138 [ 15.302056] [] ret_from_exception+0x0/0xc [ 15.338628] ---[ end trace 0a3fa0cc7f3393cd ]--- [ 15.339919] note: swapper/0[1] exited with preempt_count 1 [ 15.341995] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b [ 15.343889] SMP: stopping secondary CPUs [ 16.802836] SMP: failed to stop secondary CPUs 0-3 [ 16.806264] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]--- This patch fixes it by setting the task to current if it's NULL before accessing it. Signed-off-by: Changbin Du Fixes: 5d8544e2d0 ("RISC-V: Generic library routines and assembly") --- arch/riscv/kernel/stacktrace.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index bde85fc53357..788b65eba965 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -23,6 +23,9 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, { unsigned long fp, sp, pc; + if (!task) + task = current; + if (regs) { fp = frame_pointer(regs); sp = user_stack_pointer(regs); @@ -73,6 +76,9 @@ void notrace walk_stackframe(struct task_struct *task, unsigned long sp, pc; unsigned long *ksp; + if (!task) + task = current; + if (regs) { sp = user_stack_pointer(regs); pc = instruction_pointer(regs); -- 2.30.2