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 X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91E36C34026 for ; Tue, 18 Feb 2020 19:46:59 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4622921D56 for ; Tue, 18 Feb 2020 19:46:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=c-s.fr header.i=@c-s.fr header.b="AntGsIiZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4622921D56 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48MWZk6qFPzDqJN for ; Wed, 19 Feb 2020 06:46:54 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=c-s.fr (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@c-s.fr; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=c-s.fr header.i=@c-s.fr header.a=rsa-sha256 header.s=mail header.b=AntGsIiZ; dkim-atps=neutral Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48MWP36GmXzDqJN for ; Wed, 19 Feb 2020 06:38:31 +1100 (AEDT) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 48MWP04TdBz9v2j6; Tue, 18 Feb 2020 20:38:28 +0100 (CET) Authentication-Results: localhost; dkim=pass reason="1024-bit key; insecure key" header.d=c-s.fr header.i=@c-s.fr header.b=AntGsIiZ; dkim-adsp=pass; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id LxG3iblSf05O; Tue, 18 Feb 2020 20:38:28 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 48MWP03HQhz9v2j0; Tue, 18 Feb 2020 20:38:28 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=c-s.fr; s=mail; t=1582054708; bh=16FXGVyDUmjGA6KMYi97nEXumIjz7MvmF/4qtp6LbAI=; h=From:Subject:To:Cc:Date:From; b=AntGsIiZwJCT3RniNbT2nRmoco8sk+1EkOaa33MzNB6gJxNDRFTFSzCH/il0r6ikW uhdf/Hay2/RTudjJJKfno01BpYQpL23AsiJ9/Hnz4coUuBwi44kpRVS5Fa21+ndGaR Er+pGjYMmJ9ttKBZRln5uAn5x9x56LsB1wyizpf8= Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 763288B81D; Tue, 18 Feb 2020 20:38:28 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id e_KG-rJSnDtJ; Tue, 18 Feb 2020 20:38:28 +0100 (CET) Received: from pc16570vm.idsi0.si.c-s.fr (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 231408B80C; Tue, 18 Feb 2020 20:38:28 +0100 (CET) Received: by pc16570vm.idsi0.si.c-s.fr (Postfix, from userid 0) id B152965316; Tue, 18 Feb 2020 19:38:27 +0000 (UTC) Message-Id: <424331e2006e7291a1bfe40e7f3fa58825f565e1.1582054578.git.christophe.leroy@c-s.fr> From: Christophe Leroy Subject: [PATCH v3] powerpc/kprobes: Ignore traps that happened in real mode To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Larry Finger , Naveen N. Rao , Masami Hiramatsu Date: Tue, 18 Feb 2020 19:38:27 +0000 (UTC) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stable@kernel.vger.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Anil S Keshavamurthy , "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" When a program check exception happens while MMU translation is disabled, following Oops happens in kprobe_handler() in the following code: } else if (*addr != BREAKPOINT_INSTRUCTION) { [ 33.098554] BUG: Unable to handle kernel data access on read at 0x0000e268 [ 33.105091] Faulting instruction address: 0xc000ec34 [ 33.110010] Oops: Kernel access of bad area, sig: 11 [#1] [ 33.115348] BE PAGE_SIZE=16K PREEMPT CMPC885 [ 33.119540] Modules linked in: [ 33.122591] CPU: 0 PID: 429 Comm: cat Not tainted 5.6.0-rc1-s3k-dev-00824-g84195dc6c58a #3267 [ 33.131005] NIP: c000ec34 LR: c000ecd8 CTR: c019cab8 [ 33.136002] REGS: ca4d3b58 TRAP: 0300 Not tainted (5.6.0-rc1-s3k-dev-00824-g84195dc6c58a) [ 33.144324] MSR: 00001032 CR: 2a4d3c52 XER: 00000000 [ 33.150699] DAR: 0000e268 DSISR: c0000000 [ 33.150699] GPR00: c000b09c ca4d3c10 c66d0620 00000000 ca4d3c60 00000000 00009032 00000000 [ 33.150699] GPR08: 00020000 00000000 c087de44 c000afe0 c66d0ad0 100d3dd6 fffffff3 00000000 [ 33.150699] GPR16: 00000000 00000041 00000000 ca4d3d70 00000000 00000000 0000416d 00000000 [ 33.150699] GPR24: 00000004 c53b6128 00000000 0000e268 00000000 c07c0000 c07bb6fc ca4d3c60 [ 33.188015] NIP [c000ec34] kprobe_handler+0x128/0x290 [ 33.192989] LR [c000ecd8] kprobe_handler+0x1cc/0x290 [ 33.197854] Call Trace: [ 33.200340] [ca4d3c30] [c000b09c] program_check_exception+0xbc/0x6fc [ 33.206590] [ca4d3c50] [c000e43c] ret_from_except_full+0x0/0x4 [ 33.212392] --- interrupt: 700 at 0xe268 [ 33.270401] Instruction dump: [ 33.273335] 913e0008 81220000 38600001 3929ffff 91220000 80010024 bb410008 7c0803a6 [ 33.280992] 38210020 4e800020 38600000 4e800020 <813b0000> 6d2a7fe0 2f8a0008 419e0154 [ 33.288841] ---[ end trace 5b9152d4cdadd06d ]--- kprobe is not prepared to handle events in real mode and functions running in real mode should have been blacklisted, so kprobe_handler() can safely bail out telling 'this trap is not mine' for any trap that happened while in real-mode. If the trap happened with MSR_IR or MSR_DR cleared, return 0 immediately. Reported-by: Larry Finger Fixes: 6cc89bad60a6 ("powerpc/kprobes: Invoke handlers directly") Cc: stable@vger.kernel.org Cc: Naveen N. Rao Cc: Masami Hiramatsu Signed-off-by: Christophe Leroy --- v3: Also bail out if MSR_DR is cleared. Resending v2 with a more appropriate name v2: bailing out instead of converting real-time address to virtual and continuing. The bug might have existed even before that commit from Naveen. Signed-off-by: Christophe Leroy --- arch/powerpc/kernel/kprobes.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 2d27ec4feee4..9b340af02c38 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -264,6 +264,9 @@ int kprobe_handler(struct pt_regs *regs) if (user_mode(regs)) return 0; + if (!(regs->msr & MSR_IR) || !(regs->msr & MSR_DR)) + return 0; + /* * We don't want to be preempted for the entire * duration of kprobe processing -- 2.25.0