From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 92E3022E3FA for ; Wed, 14 May 2025 09:39:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747215545; cv=none; b=P8K7ZyHcdXGMvvzTXXbjj9vrXQjjT15ZzKm7szLoWK/g+oVmkZYILymWhSdtuW/43gMQv2Uc33AXYUmPTvx+2u30YrLEaejKv7oThmMahiPYqPKzwNb/9/MIDtbeqkewD0tuu7I49RyjMG6F8qUJ7+Z4PbjhHBFQHxsu49/pl4Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747215545; c=relaxed/simple; bh=6nYxrLW3NXCHbRW7UvNTAGjfbfQBaEqy3Bt7wmhfCvE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=iyRQtca9J5qr+zci8h5lG1AY+VgDyq1NPRGQGSaS4JJecaiqyd81q7myf52STrcBAwwtfKtV2/pUFnMICToLG1LajFwtx5UZbHRzB2pZ820yfDbBEcdkSqm38DJqXCYfVdaBk4pcFTh6L7c2rGqUUsMTQiTy9O8eZBZnTQeWHMs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8362C1688; Wed, 14 May 2025 02:38:51 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4BCB53F5A1; Wed, 14 May 2025 02:39:02 -0700 (PDT) Date: Wed, 14 May 2025 10:39:00 +0100 From: Leo Yan To: Yeoreum Yun Cc: mike.leach@linaro.org, james.clark@linaro.org, alexander.shishkin@linux.intel.com, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 3/3] coresight: prevent deactivate active config while enabling the config Message-ID: <20250514093900.GF26114@e132581.arm.com> References: <20250513170622.3071637-1-yeoreum.yun@arm.com> <20250513170622.3071637-2-yeoreum.yun@arm.com> <20250513170622.3071637-3-yeoreum.yun@arm.com> <20250513170622.3071637-4-yeoreum.yun@arm.com> <20250514093019.GE26114@e132581.arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250514093019.GE26114@e132581.arm.com> On Wed, May 14, 2025 at 10:30:19AM +0100, Leo Yan wrote: > On Tue, May 13, 2025 at 06:06:22PM +0100, Yeoreum Yun wrote: > > While enable active config via cscfg_csdev_enable_active_config(), > > active config could be deactivated via configfs' sysfs interface. > > This could make UAF issue in below scenario: > > > > CPU0 CPU1 > > (sysfs enable) load module > > cscfg_load_config_sets() > > activate config. // sysfs > > (sys_active_cnt == 1) > > ... > > cscfg_csdev_enable_active_config() > > lock(csdev->cscfg_csdev_lock) > > // here load config activate by CPU1 > > unlock(csdev->cscfg_csdev_lock) > > > > deactivate config // sysfs > > (sys_activec_cnt == 0) > > cscfg_unload_config_sets() > > unload module > > > > // access to config_desc which freed > > // while unloading module. > > cscfg_csdev_enable_config > > > > To address this, use cscfg_config_desc's active_cnt as a reference count > > which will be holded when > > - activate the config. > > - enable the activated config. > > and put the module reference when config_active_cnt == 0. > > > > Signed-off-by: Yeoreum Yun And please add a fix tag: Fixes: f8cce2ff3c04 ("coresight: syscfg: Add API to activate and enable configurations") > > --- > > .../hwtracing/coresight/coresight-config.h | 2 +- > > .../hwtracing/coresight/coresight-syscfg.c | 49 +++++++++++++------ > > 2 files changed, 35 insertions(+), 16 deletions(-) > > > > diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h > > index b9ebc9fcfb7f..90fd937d3bd8 100644 > > --- a/drivers/hwtracing/coresight/coresight-config.h > > +++ b/drivers/hwtracing/coresight/coresight-config.h > > @@ -228,7 +228,7 @@ struct cscfg_feature_csdev { > > * @feats_csdev:references to the device features to enable. > > */ > > struct cscfg_config_csdev { > > - const struct cscfg_config_desc *config_desc; > > + struct cscfg_config_desc *config_desc; > > struct coresight_device *csdev; > > bool enabled; > > struct list_head node; > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > > index 5d194b9269f5..6d8c212ad434 100644 > > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > > @@ -870,6 +870,25 @@ void cscfg_csdev_reset_feats(struct coresight_device *csdev) > > } > > EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats); > > > > +static bool cscfg_config_desc_get(struct cscfg_config_desc *config_desc) > > I would like to change the return type to int, so the error is handled > within the function. As a result, the caller _cscfg_activate_config() > does not need to explicitly return an error value. > > Otherwise, the patch looks good to me. > > Thanks, > Leo > > > +{ > > + if (!atomic_fetch_inc(&config_desc->active_cnt)) { > > + /* must ensure that config cannot be unloaded in use */ > > + if (unlikely(cscfg_owner_get(config_desc->load_owner))) { > > + atomic_dec(&config_desc->active_cnt); > > + return false; > > + } > > + } > > + > > + return true; > > +} > > + > > +static void cscfg_config_desc_put(struct cscfg_config_desc *config_desc) > > +{ > > + if (!atomic_dec_return(&config_desc->active_cnt)) > > + cscfg_owner_put(config_desc->load_owner); > > +} > > + > > /* > > * This activate configuration for either perf or sysfs. Perf can have multiple > > * active configs, selected per event, sysfs is limited to one. > > @@ -893,22 +912,17 @@ static int _cscfg_activate_config(unsigned long cfg_hash) > > if (config_desc->available == false) > > return -EBUSY; > > > > - /* must ensure that config cannot be unloaded in use */ > > - err = cscfg_owner_get(config_desc->load_owner); > > - if (err) > > + if (!cscfg_config_desc_get(config_desc)) { > > + err = -EINVAL; > > break; > > + } > > + > > /* > > * increment the global active count - control changes to > > * active configurations > > */ > > atomic_inc(&cscfg_mgr->sys_active_cnt); > > > > - /* > > - * mark the descriptor as active so enable config on a > > - * device instance will use it > > - */ > > - atomic_inc(&config_desc->active_cnt); > > - > > err = 0; > > dev_dbg(cscfg_device(), "Activate config %s.\n", config_desc->name); > > break; > > @@ -923,9 +937,8 @@ static void _cscfg_deactivate_config(unsigned long cfg_hash) > > > > list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) { > > if ((unsigned long)config_desc->event_ea->var == cfg_hash) { > > - atomic_dec(&config_desc->active_cnt); > > atomic_dec(&cscfg_mgr->sys_active_cnt); > > - cscfg_owner_put(config_desc->load_owner); > > + cscfg_config_desc_put(config_desc); > > dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name); > > break; > > } > > @@ -1050,7 +1063,7 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > > unsigned long cfg_hash, int preset) > > { > > struct cscfg_config_csdev *config_csdev_active = NULL, *config_csdev_item; > > - const struct cscfg_config_desc *config_desc; > > + struct cscfg_config_desc *config_desc; > > unsigned long flags; > > int err = 0; > > > > @@ -1065,8 +1078,8 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > > raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); > > list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) { > > config_desc = config_csdev_item->config_desc; > > - if ((atomic_read(&config_desc->active_cnt)) && > > - ((unsigned long)config_desc->event_ea->var == cfg_hash)) { > > + if (((unsigned long)config_desc->event_ea->var == cfg_hash) && > > + cscfg_config_desc_get(config_desc)) { > > config_csdev_active = config_csdev_item; > > csdev->active_cscfg_ctxt = (void *)config_csdev_active; > > break; > > @@ -1100,7 +1113,11 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > > err = -EBUSY; > > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > > } > > + > > + if (err) > > + cscfg_config_desc_put(config_desc); > > } > > + > > return err; > > } > > EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); > > @@ -1139,8 +1156,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev) > > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > > > > /* true if there was an enabled active config */ > > - if (config_csdev) > > + if (config_csdev) { > > cscfg_csdev_disable_config(config_csdev); > > + cscfg_config_desc_put(config_csdev->config_desc); > > + } > > } > > EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config); > > > > -- > > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} > > > _______________________________________________ > CoreSight mailing list -- coresight@lists.linaro.org > To unsubscribe send an email to coresight-leave@lists.linaro.org