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 85A34C7EE2C for ; Sun, 28 May 2023 19:28:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230142AbjE1T23 (ORCPT ); Sun, 28 May 2023 15:28:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230139AbjE1T23 (ORCPT ); Sun, 28 May 2023 15:28:29 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23374A7 for ; Sun, 28 May 2023 12:28:28 -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 A788B61040 for ; Sun, 28 May 2023 19:28:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C6BA6C433D2; Sun, 28 May 2023 19:28:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685302107; bh=j5vvx8VTbcx7YDeHezKVoK1v+mS/DTAgrOeEYFBUoY8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N92em4+akuwDmzpH8vspHhV30g3kAWDwjF2C9kLGW1xTqoUo/V4Tb1yt+NSeb0Uzs HyJkeDY66cfEqclIFih3TpYgKBgFCymRDukKso99Yr8CEbUqxMBs1MeGut4ipIVrnR XukHHE6rU9DS5PmWCfsHIYoBNfQrUKFog7m8Vq8M= 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 5.4 156/161] x86/show_trace_log_lvl: Ensure stack pointer is aligned, again Date: Sun, 28 May 2023 20:11:20 +0100 Message-Id: <20230528190841.797032591@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190837.051205996@linuxfoundation.org> References: <20230528190837.051205996@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