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 150CCC53210 for ; Wed, 4 Jan 2023 16:19:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239901AbjADQTA (ORCPT ); Wed, 4 Jan 2023 11:19:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239905AbjADQSh (ORCPT ); Wed, 4 Jan 2023 11:18:37 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7313B8FFA for ; Wed, 4 Jan 2023 08:18:36 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 29559B817AE for ; Wed, 4 Jan 2023 16:18:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84DB6C43396; Wed, 4 Jan 2023 16:18:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672849113; bh=Shpcuz+N78hWLl6cfi9aW9DgtYZPVLJ7BAA8JqbfG2c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WougLCpXt4Qb9cnfAcbXcdWfVXB12Hb6LaGJjihhhMDKthZmoEQcarFaF1B9cI7/T kET7Xe2vXDlvbVNu2k5XbQ0cHvhfN2LMduTTME5UiwvqRFCBM0m4v8tL0DLkOLZu3l Rz2bXcBXbLsHqfVSWWRDer58jyp7zjGX4Av1VxNs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peter Zijlstra , "Masami Hiramatsu (Google)" Subject: [PATCH 6.0 065/177] x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK Date: Wed, 4 Jan 2023 17:05:56 +0100 Message-Id: <20230104160509.625774247@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230104160507.635888536@linuxfoundation.org> References: <20230104160507.635888536@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: Masami Hiramatsu (Google) commit 1993bf97992df2d560287f3c4120eda57426843d upstream. Since the CONFIG_RETHUNK and CONFIG_SLS will use INT3 for stopping speculative execution after RET instruction, kprobes always failes to check the probed instruction boundary by decoding the function body if the probed address is after such sequence. (Note that some conditional code blocks will be placed after function return, if compiler decides it is not on the hot path.) This is because kprobes expects kgdb puts the INT3 as a software breakpoint and it will replace the original instruction. But these INT3 are not such purpose, it doesn't need to recover the original instruction. To avoid this issue, kprobes checks whether the INT3 is owned by kgdb or not, and if so, stop decoding and make it fail. The other INT3 will come from CONFIG_RETHUNK/CONFIG_SLS and those can be treated as a one-byte instruction. Fixes: e463a09af2f0 ("x86: Add straight-line-speculation mitigation") Suggested-by: Peter Zijlstra Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/167146051026.1374301.392728975473572291.stgit@devnote3 Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/kprobes/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include #include @@ -283,12 +284,15 @@ static int can_probe(unsigned long paddr if (ret < 0) return 0; +#ifdef CONFIG_KGDB /* - * Another debugging subsystem might insert this breakpoint. - * In that case, we can't recover it. + * If there is a dynamically installed kgdb sw breakpoint, + * this function should not be probed. */ - if (insn.opcode.bytes[0] == INT3_INSN_OPCODE) + if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && + kgdb_has_hit_break(addr)) return 0; +#endif addr += insn.length; }