From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DEF7611B for ; Sun, 28 May 2023 19:37:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7736DC433EF; Sun, 28 May 2023 19:37:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685302665; bh=Ima5WBTGAQip3VNZZXYRFN57qAXgEIT9Tl8MIGXwSL8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ddAXyyyTMOydi+h9NQ8L+hMyqe/nGy8Qqh04Flc0DIkVOWlBv3Otq2Omd78xhkGUp ZrQLL4A4VTJNKIKcHUlE+NoIURKCoO/mxU0oB4aq0WgjPnf89/GL6QoXOWaRzvKhZg VSOo8Atf6/YToH32nQ2sx9oVX+VbPj3jnZiNy9Ek= 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 6.1 095/119] x86/show_trace_log_lvl: Ensure stack pointer is aligned, again Date: Sun, 28 May 2023 20:11:35 +0100 Message-Id: <20230528190838.692923735@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190835.386670951@linuxfoundation.org> References: <20230528190835.386670951@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 @@ -195,7 +195,6 @@ static void show_trace_log_lvl(struct ta 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); /* @@ -214,9 +213,13 @@ static void show_trace_log_lvl(struct ta * - 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