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=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 02D45C4320E for ; Tue, 10 Aug 2021 17:52:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE59F61073 for ; Tue, 10 Aug 2021 17:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235638AbhHJRw0 (ORCPT ); Tue, 10 Aug 2021 13:52:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:56806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237315AbhHJRuW (ORCPT ); Tue, 10 Aug 2021 13:50:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8C71161076; Tue, 10 Aug 2021 17:42:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1628617358; bh=VX9BCv/xjhp3lzPf4kDY4Ob7smi3OWrnyPp1j+Ehe5U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dMPTKutpoyHzbQWbHLdtNyziNG65G6vUVC07QZLbe7XIrmOdeeS9oJHXs8asfZTK6 FXZbGPKRylMsp2kmMIFc+NgBSvXKem/bAFyLfXswjQHJKG7MNh6XBI2a8pnJ29jBFh +OE5aqrtFoa9kDIhX1Y6Zob1WWZbWSDIhBU/JEds= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jisheng Zhang , Atish Patra , Wende Tan , Palmer Dabbelt , Sasha Levin Subject: [PATCH 5.13 023/175] riscv: stacktrace: Fix NULL pointer dereference Date: Tue, 10 Aug 2021 19:28:51 +0200 Message-Id: <20210810173001.717955153@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210810173000.928681411@linuxfoundation.org> References: <20210810173000.928681411@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jisheng Zhang [ Upstream commit 78d9d8005e4556448f398d876f29d0ca7ab8e398 ] When CONFIG_FRAME_POINTER=y, calling dump_stack() can always trigger NULL pointer dereference panic similar as below: [ 0.396060] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5+ #47 [ 0.396692] Hardware name: riscv-virtio,qemu (DT) [ 0.397176] Call Trace: [ 0.398191] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000960 [ 0.399487] Oops [#1] [ 0.399739] Modules linked in: [ 0.400135] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5+ #47 [ 0.400570] Hardware name: riscv-virtio,qemu (DT) [ 0.400926] epc : walk_stackframe+0xc4/0xdc [ 0.401291] ra : dump_backtrace+0x30/0x38 [ 0.401630] epc : ffffffff80004922 ra : ffffffff8000496a sp : ffffffe000f3bd00 [ 0.402115] gp : ffffffff80cfdcb8 tp : ffffffe000f30000 t0 : ffffffff80d0b0cf [ 0.402602] t1 : ffffffff80d0b0c0 t2 : 0000000000000000 s0 : ffffffe000f3bd60 [ 0.403071] s1 : ffffffff808bc2e8 a0 : 0000000000001000 a1 : 0000000000000000 [ 0.403448] a2 : ffffffff803d7088 a3 : ffffffff808bc2e8 a4 : 6131725dbc24d400 [ 0.403820] a5 : 0000000000001000 a6 : 0000000000000002 a7 : ffffffffffffffff [ 0.404226] s2 : 0000000000000000 s3 : 0000000000000000 s4 : 0000000000000000 [ 0.404634] s5 : ffffffff803d7088 s6 : ffffffff808bc2e8 s7 : ffffffff80630650 [ 0.405085] s8 : ffffffff80912a80 s9 : 0000000000000008 s10: ffffffff804000fc [ 0.405388] s11: 0000000000000000 t3 : 0000000000000043 t4 : ffffffffffffffff [ 0.405616] t5 : 000000000000003d t6 : ffffffe000f3baa8 [ 0.405793] status: 0000000000000100 badaddr: 0000000000000960 cause: 000000000000000d [ 0.406135] [] walk_stackframe+0xc4/0xdc [ 0.407032] [] dump_backtrace+0x30/0x38 [ 0.407797] [] show_stack+0x40/0x4c [ 0.408234] [] dump_stack+0x90/0xb6 [ 0.409019] [] ptdump_init+0x20/0xc4 [ 0.409681] [] do_one_initcall+0x4c/0x226 [ 0.410110] [] kernel_init_freeable+0x1f4/0x258 [ 0.410562] [] kernel_init+0x22/0x148 [ 0.410959] [] ret_from_exception+0x0/0x14 [ 0.412241] ---[ end trace b2ab92c901b96251 ]--- [ 0.413099] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b The reason is the task is NULL when we finally call walk_stackframe() the NULL is passed from __dump_stack(): |static void __dump_stack(void) |{ | dump_stack_print_info(KERN_DEFAULT); | show_stack(NULL, NULL, KERN_DEFAULT); |} Fix this issue by checking "task == NULL" case in walk_stackframe(). Fixes: eac2f3059e02 ("riscv: stacktrace: fix the riscv stacktrace when CONFIG_FRAME_POINTER enabled") Signed-off-by: Jisheng Zhang Reviewed-by: Atish Patra Tested-by: Wende Tan Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin --- arch/riscv/kernel/stacktrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c index bde85fc53357..7bc8af75933a 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -27,7 +27,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs, fp = frame_pointer(regs); sp = user_stack_pointer(regs); pc = instruction_pointer(regs); - } else if (task == current) { + } else if (task == NULL || task == current) { fp = (unsigned long)__builtin_frame_address(1); sp = (unsigned long)__builtin_frame_address(0); pc = (unsigned long)__builtin_return_address(0); -- 2.30.2