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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F95EC77B7C for ; Sun, 28 May 2023 19:21:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229938AbjE1TVa (ORCPT ); Sun, 28 May 2023 15:21:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229931AbjE1TVa (ORCPT ); Sun, 28 May 2023 15:21:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 860ABC7 for ; Sun, 28 May 2023 12:21:28 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 201AF61B1C for ; Sun, 28 May 2023 19:21:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FBC0C433EF; Sun, 28 May 2023 19:21:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685301687; bh=j5vvx8VTbcx7YDeHezKVoK1v+mS/DTAgrOeEYFBUoY8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=StUTCl1iT3a4i8kkLaIy5MRHAPgERKp1IGEhxEiJVes2LXFKRQZn6WD8R24FVy4+W 2Qq1IToYXYVVgTYyRb5dXrBqDt9MAd4gWTfsbL758bc2mOY5M9JUUxt8cTVY+FMylV sxilTFE6Ykq882aGAVKNXlqaY/qjlkQLiTDlUKM0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vernon Lovejoy , Oleg Nesterov , Josh Poimboeuf Subject: [PATCH 4.19 129/132] x86/show_trace_log_lvl: Ensure stack pointer is aligned, again Date: Sun, 28 May 2023 20:11:08 +0100 Message-Id: <20230528190837.832657095@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190833.565872088@linuxfoundation.org> References: <20230528190833.565872088@linuxfoundation.org> User-Agent: quilt/0.67 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: Vernon Lovejoy commit 2e4be0d011f21593c6b316806779ba1eba2cd7e0 upstream. The commit e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned") tried to align the stack pointer in show_trace_log_lvl(), otherwise the "stack < stack_info.end" check can't guarantee that the last read does not go past the end of the stack. However, we have the same problem with the initial value of the stack pointer, it can also be unaligned. So without this patch this trivial kernel module #include static int init(void) { asm volatile("sub $0x4,%rsp"); dump_stack(); asm volatile("add $0x4,%rsp"); return -EAGAIN; } module_init(init); MODULE_LICENSE("GPL"); crashes the kernel. Fixes: e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned") Signed-off-by: Vernon Lovejoy Signed-off-by: Oleg Nesterov Link: https://lore.kernel.org/r/20230512104232.GA10227@redhat.com Signed-off-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/dumpstack.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -171,7 +171,6 @@ void show_trace_log_lvl(struct task_stru printk("%sCall Trace:\n", log_lvl); unwind_start(&state, task, regs, stack); - stack = stack ? : get_stack_pointer(task, regs); regs = unwind_get_entry_regs(&state, &partial); /* @@ -190,9 +189,13 @@ void show_trace_log_lvl(struct task_stru * - hardirq stack * - entry stack */ - for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { + for (stack = stack ?: get_stack_pointer(task, regs); + stack; + stack = stack_info.next_sp) { const char *stack_name; + stack = PTR_ALIGN(stack, sizeof(long)); + if (get_stack_info(stack, task, &stack_info, &visit_mask)) { /* * We weren't on a valid stack. It's possible that