From patchwork Mon Jul 22 21:06:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lucas De Marchi X-Patchwork-Id: 13739097 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 14ADBC3DA7E for ; Mon, 22 Jul 2024 21:07:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DDF4810E336; Mon, 22 Jul 2024 21:07:25 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="iLjjtSt6"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) by gabe.freedesktop.org (Postfix) with ESMTPS id 74CAF10E310; Mon, 22 Jul 2024 21:07:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1721682421; x=1753218421; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jzjRmAv0FQC+DoGcPDLeFGLEdXtORRGXZvIMK7w3hGY=; b=iLjjtSt6gdW4pvvvqV9LwxRlrJu8GgdaZgP8d9j1DVY2PtKmDWtzzeco 7eKUE9Nd6Oh+26VNxLhqqqRrgWA1hdm+as9x/qIi/Mpuyp5PfDv0g0WMo KJ6phPLtjg6ZetqJWmiBjawZkRr1ePMEGv34A3W5wC0xhFHiDt/sR1BYc MPfRUP+xQQ5Hshmp7GHMc820bvsJL3Pg/zaCrbaX/lJihaoaA4kFlRXBK nHsQMR6PBtXbhqaQ5mu79nlyxrLROGNqVjFu1uTje52hOLQqCg8+eJJ8E 78GgDX6BvmiAmL2xzBF0oG9qW74/b3yTPC8FPcadbgMt1yxoEq3GA6SnH w==; X-CSE-ConnectionGUID: HvyoQgELQSORbAtTGNFhcw== X-CSE-MsgGUID: mnazB1eKS+OxFNWpojThdg== X-IronPort-AV: E=McAfee;i="6700,10204,11141"; a="30428291" X-IronPort-AV: E=Sophos;i="6.09,229,1716274800"; d="scan'208";a="30428291" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2024 14:07:00 -0700 X-CSE-ConnectionGUID: +sqI0r3xT7aWlDU75JtWiQ== X-CSE-MsgGUID: 3F7AwXZ2T6eMmuT0vcHHCg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,229,1716274800"; d="scan'208";a="51653273" Received: from lucas-s2600cw.jf.intel.com ([10.165.21.196]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jul 2024 14:07:00 -0700 From: Lucas De Marchi To: intel-gfx@lists.freedesktop.org, linux-perf-users@vger.kernel.org Cc: Tvrtko Ursulin , dri-devel@lists.freedesktop.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Lucas De Marchi Subject: [PATCH 1/7] perf/core: Add pmu get/put Date: Mon, 22 Jul 2024 14:06:42 -0700 Message-ID: <20240722210648.80892-2-lucas.demarchi@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240722210648.80892-1-lucas.demarchi@intel.com> References: <20240722210648.80892-1-lucas.demarchi@intel.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" If a pmu is unregistered while there's an active event, perf will still access the pmu via event->pmu, even after the event is destroyed. This makes it difficult for drivers like i915 that take a reference on the device when the event is created and put it when it's destroyed. Currently the following use-after-free happens just after destroying the event: BUG: KASAN: use-after-free in exclusive_event_destroy+0xd8/0xf0 Read of size 4 at addr ffff88816e2bb63c by task perf/7748 Whenever and event is created, get a pmu reference to use in event->pmu and just before calling module_put(), drop the reference.. Signed-off-by: Lucas De Marchi --- include/linux/perf_event.h | 3 +++ kernel/events/core.c | 32 ++++++++++++++++++++++++++++---- 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index a5304ae8c654..7048a505e93c 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -540,6 +540,9 @@ struct pmu { * Check period value for PERF_EVENT_IOC_PERIOD ioctl. */ int (*check_period) (struct perf_event *event, u64 value); /* optional */ + + struct pmu *(*get) (struct pmu *pmu); /* optional: get a reference */ + void (*put) (struct pmu *pmu); /* optional: put a reference */ }; enum perf_addr_filter_action_t { diff --git a/kernel/events/core.c b/kernel/events/core.c index 1b6f5dc7ed32..cc7541b644b0 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5208,6 +5208,8 @@ static void perf_addr_filters_splice(struct perf_event *event, static void _free_event(struct perf_event *event) { + struct module *module; + irq_work_sync(&event->pending_irq); unaccount_event(event); @@ -5259,7 +5261,13 @@ static void _free_event(struct perf_event *event) put_ctx(event->ctx); exclusive_event_destroy(event); - module_put(event->pmu->module); + + module = event->pmu->module; + event->pmu->put(event->pmu); + /* can't touch pmu anymore */ + event->pmu = NULL; + + module_put(module); call_rcu(&event->rcu_head, free_event_rcu); } @@ -11331,6 +11339,11 @@ static int perf_pmu_nop_int(struct pmu *pmu) return 0; } +static struct pmu *perf_pmu_nop_pmu(struct pmu *pmu) +{ + return pmu; +} + static int perf_event_nop_int(struct perf_event *event, u64 value) { return 0; @@ -11617,6 +11630,12 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) if (!pmu->event_idx) pmu->event_idx = perf_event_idx_default; + if (!pmu->get) + pmu->get = perf_pmu_nop_pmu; + + if (!pmu->put) + pmu->put = perf_pmu_nop_void; + list_add_rcu(&pmu->entry, &pmus); atomic_set(&pmu->exclusive_cnt, 0); ret = 0; @@ -11695,7 +11714,8 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) BUG_ON(!ctx); } - event->pmu = pmu; + event->pmu = pmu->get(pmu); + ret = pmu->event_init(event); if (ctx) @@ -11714,8 +11734,12 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) event->destroy(event); } - if (ret) - module_put(pmu->module); + if (ret) { + struct module *module = pmu->module; + + pmu->put(pmu); + module_put(module); + } return ret; }