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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no 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 67129C4363D for ; Wed, 7 Oct 2020 13:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07A9D20789 for ; Wed, 7 Oct 2020 13:01:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="SLBNnzxk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728360AbgJGNBB (ORCPT ); Wed, 7 Oct 2020 09:01:01 -0400 Received: from m42-4.mailgun.net ([69.72.42.4]:33796 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728283AbgJGNBB (ORCPT ); Wed, 7 Oct 2020 09:01:01 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1602075659; h=Content-Transfer-Encoding: MIME-Version: Message-Id: Date: Subject: Cc: To: From: Sender; bh=Ampq9i94Z2y+v4ESFzjpNequ3NQaL38eIA6M3XkpyyU=; b=SLBNnzxkXeqyN8qgx5RWmtt2q4t14MXIJRNpzCRXdw/FvUaGHxRmp2wgMn7FERcWb4jKE2OK Q9Qadd/RCpFLAB/tfk6RACQ3HJ3rWGrv0df7ssQtcOiXhy/UZi7ANAMiO7bLYVkgQ+X+dt6t mp/oGkj+UB5YypU+KiQuyqpMaWg= X-Mailgun-Sending-Ip: 69.72.42.4 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n07.prod.us-west-2.postgun.com with SMTP id 5f7dbbf9d6d00c7a9e29a098 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 07 Oct 2020 13:00:41 GMT Sender: saiprakash.ranjan=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id A5801C433FF; Wed, 7 Oct 2020 13:00:41 +0000 (UTC) Received: from blr-ubuntu-253.qualcomm.com (blr-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.18.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 105FAC433CB; Wed, 7 Oct 2020 13:00:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 105FAC433CB Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=saiprakash.ranjan@codeaurora.org From: Sai Prakash Ranjan To: Mathieu Poirier , Suzuki K Poulose , Mike Leach Cc: coresight@lists.linaro.org, Stephen Boyd , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, denik@google.com, leo.yan@linaro.org, peterz@infradead.org, Sai Prakash Ranjan Subject: [PATCH 0/2] coresight: etf/etb: NULL Pointer dereference crash fixes Date: Wed, 7 Oct 2020 18:30:23 +0530 Message-Id: X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org There was a report of NULL pointer dereference in ETF enable path for perf CS mode with PID monitoring. It is almost 100% reproducible when the process to monitor is something very active such as chrome and with ETF as the sink and not ETR. Currently in a bid to find the pid, the owner is dereferenced via task_pid_nr() call in tmc_enable_etf_sink_perf() and with owner being NULL, we get a NULL pointer dereference. Looking at the ETR and other places in the kernel, ETF and the ETB are the only places trying to dereference the task(owner) in tmc_enable_etf_sink_perf() which is also called from the sched_in path as in the call trace. Owner(task) is NULL even in the case of ETR in tmc_enable_etr_sink_perf(), but since we cache the PID in alloc_buffer() callback and it is done as part of etm_setup_aux() when allocating buffer for ETR sink, we never dereference this NULL pointer and we are safe. So lets do the same thing with ETF and ETB and cache the PID to which the cs_buffer belongs in alloc_buffer() callback for ETF and ETB as done for ETR. This will also remove the unnecessary function calls (task_pid_nr()) in tmc_enable_etr_sink_perf() and etb_enable_perf(). Easily reproducible running below: perf record -e cs_etm/@tmc_etf0/ -N -p Unable to handle kernel NULL pointer dereference at virtual address 0000000000000548 Mem abort info: ESR = 0x96000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 ... Call trace: tmc_enable_etf_sink+0xe4/0x280 coresight_enable_path+0x168/0x1fc etm_event_start+0x8c/0xf8 etm_event_add+0x38/0x54 event_sched_in+0x194/0x2ac group_sched_in+0x54/0x12c flexible_sched_in+0xd8/0x120 visit_groups_merge+0x100/0x16c ctx_flexible_sched_in+0x50/0x74 ctx_sched_in+0xa4/0xa8 perf_event_sched_in+0x60/0x6c perf_event_context_sched_in+0x98/0xe0 __perf_event_task_sched_in+0x5c/0xd8 finish_task_switch+0x184/0x1cc schedule_tail+0x20/0xec ret_from_fork+0x4/0x18 Sai Prakash Ranjan (2): coresight: tmc-etf: Fix NULL ptr dereference in tmc_enable_etf_sink_perf() coresight: etb10: Fix possible NULL ptr dereference in etb_enable_perf() drivers/hwtracing/coresight/coresight-etb10.c | 4 +++- drivers/hwtracing/coresight/coresight-priv.h | 2 ++ drivers/hwtracing/coresight/coresight-tmc-etf.c | 4 +++- 3 files changed, 8 insertions(+), 2 deletions(-) base-commit: 3477326277451000bc667dfcc4fd0774c039184c -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation