From nobody Fri Jan 2 20:37:50 2026 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 218A5E95A82 for ; Sun, 8 Oct 2023 10:30:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344620AbjJHKam (ORCPT ); Sun, 8 Oct 2023 06:30:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230412AbjJHKai (ORCPT ); Sun, 8 Oct 2023 06:30:38 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3792EC6; Sun, 8 Oct 2023 03:30:36 -0700 (PDT) Date: Sun, 08 Oct 2023 10:30:33 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1696761034; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=RFcgvCwtBkHjmjC5Kv59Tho8cI5sB4+dK7KBM8mjgEo=; b=kwiLjNQmuwlGGMi4EdsYkoz71pGXXZ0BIeUR/pN0bHENed0HdVB5+vK3OF7d+KDAAoCEUI Whqe2DtedUA5cOuGrJPI2iJlkIWFwVa66lWwv9z8LcybXPAzzWLUbRYR9Df7zgEO9j7ZAM sDf6+Oa16Tnkk/xwVb70G00/wvx0HzrmyQoqtsRKTYz80CyJy8jBYt0wdEEuC35UedBXPI xStItsIqbw+xG/xqkUtPCPM1o7JPCmaPw1H6r/OaTPhysn7YE9MdfXb2gZqZsXaXvxJxS7 Ze2teRbhAUuDpCTxuSGrCMSSjh14BhtUT8oY68E3mD3lxF6vHYftgJrmgZjvXQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1696761034; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=RFcgvCwtBkHjmjC5Kv59Tho8cI5sB4+dK7KBM8mjgEo=; b=5SsDrl6Fd6RtNGDTB9P4PsIR2dJg2M//yECJsaid/TgeB4fr3GRxMotUyQpq8FXQP6/eoW BcWllE6zz6s4WcCA== From: "tip-bot2 for JP Kobryn" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] perf/x86/lbr: Filter vsyscall addresses Cc: Alexei Starovoitov , JP Kobryn , Ingo Molnar , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <169676103391.3135.1323905069105939036.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the perf/urgent branch of tip: Commit-ID: e53899771a02f798d436655efbd9d4b46c0f9265 Gitweb: https://git.kernel.org/tip/e53899771a02f798d436655efbd9d4b46= c0f9265 Author: JP Kobryn AuthorDate: Fri, 06 Oct 2023 11:57:26 -07:00 Committer: Ingo Molnar CommitterDate: Sun, 08 Oct 2023 12:25:18 +02:00 perf/x86/lbr: Filter vsyscall addresses We found that a panic can occur when a vsyscall is made while LBR sampling is active. If the vsyscall is interrupted (NMI) for perf sampling, this call sequence can occur (most recent at top): __insn_get_emulate_prefix() insn_get_emulate_prefix() insn_get_prefixes() insn_get_opcode() decode_branch_type() get_branch_type() intel_pmu_lbr_filter() intel_pmu_handle_irq() perf_event_nmi_handler() Within __insn_get_emulate_prefix() at frame 0, a macro is called: peek_nbyte_next(insn_byte_t, insn, i) Within this macro, this dereference occurs: (insn)->next_byte Inspecting registers at this point, the value of the next_byte field is the address of the vsyscall made, for example the location of the vsyscall version of gettimeofday() at 0xffffffffff600000. The access to an address in the vsyscall region will trigger an oops due to an unhandled page fault. To fix the bug, filtering for vsyscalls can be done when determining the branch type. This patch will return a "none" branch if a kernel address if found to lie in the vsyscall region. Suggested-by: Alexei Starovoitov Signed-off-by: JP Kobryn Signed-off-by: Ingo Molnar Cc: stable@vger.kernel.org --- arch/x86/events/utils.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/utils.c b/arch/x86/events/utils.c index 76b1f8b..dab4ed1 100644 --- a/arch/x86/events/utils.c +++ b/arch/x86/events/utils.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 #include +#include =20 #include "perf_event.h" =20 @@ -132,9 +133,9 @@ static int get_branch_type(unsigned long from, unsigned= long to, int abort, * The LBR logs any address in the IP, even if the IP just * faulted. This means userspace can control the from address. * Ensure we don't blindly read any address by validating it is - * a known text address. + * a known text address and not a vsyscall address. */ - if (kernel_text_address(from)) { + if (kernel_text_address(from) && !in_gate_area_no_mm(from)) { addr =3D (void *)from; /* * Assume we can get the maximum possible size