From nobody Thu Apr 9 04:42:14 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 8B731C4332F for ; Wed, 2 Nov 2022 13:06:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230317AbiKBNGr (ORCPT ); Wed, 2 Nov 2022 09:06:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231269AbiKBNGn (ORCPT ); Wed, 2 Nov 2022 09:06:43 -0400 Received: from smtpout.efficios.com (smtpout.efficios.com [IPv6:2607:5300:203:5aae::31e5]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A49EBCAE; Wed, 2 Nov 2022 06:06:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1667394398; bh=BGBLi28IGb/j9Rsc8sOXjZnGnF7UAm518xzGIru/4uI=; h=From:To:Cc:Subject:Date:From; b=E400qiJQMQb/70O6znFxeZi92l/uqb80PsPOgXu3cvpXHsXWob/LCsWOnqePjlsoV OpAUYHN/JmjyNSGguieK/2hwDo7nn5gn/MnAeaWoSR7SbRPZ0v6nnU2sCfyrMUYxvV uyNBXx645mma6vnH8qOtLVf7LZh/kYfkWFxC2HFTv2qAcs/HhyheQtOy+daB8GEKIf R31nAD3B5pZhOQkMAnntr+9C9DGZmNia1+QA7gAyxSesFVjsxTBdgBVndkhfZWCtSY DAEoACQBtL5Cod5rQ4JJPyKTtpwI45wmyWwNfYmlQewJSixa0lNUJl7JjGWWmSFeZq iSA79j3rAhf4w== Received: from thinkos.internal.efficios.com (192-222-180-24.qc.cable.ebox.net [192.222.180.24]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4N2Rwt4HwVzfTB; Wed, 2 Nov 2022 09:06:38 -0400 (EDT) From: Mathieu Desnoyers To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "Paul E . McKenney" , Boqun Feng , "H . Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, Peter Oskolkov , Mathieu Desnoyers , Mark Rutland Subject: [PATCH] rseq: Use pr_warn_once() when deprecated/unknown ABI flags are encountered Date: Wed, 2 Nov 2022 09:06:35 -0400 Message-Id: <20221102130635.7379-1-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" These commits use WARN_ON_ONCE() and kill the offending processes when deprecated and unknown flags are encountered: commit c17a6ff93213 ("rseq: Kill process when unknown flags are encountered= in ABI structures") commit 0190e4198e47 ("rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags") The WARN_ON_ONCE() triggered by userspace input prevents use of Syzkaller to fuzz the rseq system call. Replace this WARN_ON_ONCE() by pr_warn_once() messages which contain actually useful information. Reported-by: Mark Rutland Signed-off-by: Mathieu Desnoyers Acked-by: Mark Rutland Acked-by: Paul E. McKenney --- kernel/rseq.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/kernel/rseq.c b/kernel/rseq.c index bda8175f8f99..d38ab944105d 100644 --- a/kernel/rseq.c +++ b/kernel/rseq.c @@ -171,12 +171,27 @@ static int rseq_get_rseq_cs(struct task_struct *t, st= ruct rseq_cs *rseq_cs) return 0; } =20 +static bool rseq_warn_flags(const char *str, u32 flags) +{ + u32 test_flags; + + if (!flags) + return false; + test_flags =3D flags & RSEQ_CS_NO_RESTART_FLAGS; + if (test_flags) + pr_warn_once("Deprecated flags (%u) in %s ABI structure", test_flags, st= r); + test_flags =3D flags & ~RSEQ_CS_NO_RESTART_FLAGS; + if (test_flags) + pr_warn_once("Unknown flags (%u) in %s ABI structure", test_flags, str); + return true; +} + static int rseq_need_restart(struct task_struct *t, u32 cs_flags) { u32 flags, event_mask; int ret; =20 - if (WARN_ON_ONCE(cs_flags & RSEQ_CS_NO_RESTART_FLAGS) || cs_flags) + if (rseq_warn_flags("rseq_cs", cs_flags)) return -EINVAL; =20 /* Get thread flags. */ @@ -184,7 +199,7 @@ static int rseq_need_restart(struct task_struct *t, u32= cs_flags) if (ret) return ret; =20 - if (WARN_ON_ONCE(flags & RSEQ_CS_NO_RESTART_FLAGS) || flags) + if (rseq_warn_flags("rseq", flags)) return -EINVAL; =20 /* --=20 2.30.2