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Message-ID:
<PA6PR08MB1052667843120D0736A4B574AFBD02@PA6PR08MB10526.eurprd08.prod.outlook.com>
Date: Wed, 12 Mar 2025 06:36:29 +0000
From: Yeo Reum Yun <YeoReum.Yun@....com>
To: Suzuki Poulose <Suzuki.Poulose@....com>, "mike.leach@...aro.org"
<mike.leach@...aro.org>, "james.clark@...aro.org" <james.clark@...aro.org>,
"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>
CC: "coresight@...ts.linaro.org" <coresight@...ts.linaro.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/1] coresight: prevent deactivate active config while
enabling the config
Gentle ping in case of forgotten,..
________________________________________
From: Yeoreum Yun <yeoreum.yun@....com>
Sent: 09 January 2025 17:19
To: Suzuki Poulose; mike.leach@...aro.org; james.clark@...aro.org; alexander.shishkin@...ux.intel.com
Cc: coresight@...ts.linaro.org; linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; Yeo Reum Yun
Subject: [PATCH v3 1/1] coresight: prevent deactivate active config while enabling the config
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.
cfs_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 <yeoreum.yun@....com>
---
from v2 to v3:
- add cscfg_config_desc_get()/put() (from Suzuki).
- remove sys_enable_cnt.
from v1 to v2:
- modify commit message.
---
.../hwtracing/coresight/coresight-config.h | 2 +-
.../coresight/coresight-etm4x-core.c | 3 +
.../hwtracing/coresight/coresight-syscfg.c | 55 ++++++++++++++-----
3 files changed, 44 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-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 86893115df17..6218ef40acbc 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -986,6 +986,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1);
raw_spin_unlock(&drvdata->spinlock);
+
+ cscfg_csdev_disable_active_config(csdev);
+
cpus_read_unlock();
/*
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index a70c1454b410..8766f72db33e 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -391,14 +391,17 @@ static void cscfg_owner_put(struct cscfg_load_owner_info *owner_info)
static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner)
{
struct cscfg_config_csdev *config_csdev, *tmp;
+ unsigned long flags;
if (list_empty(&csdev->config_csdev_list))
return;
+ raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
list_for_each_entry_safe(config_csdev, tmp, &csdev->config_csdev_list, node) {
if (config_csdev->config_desc->load_owner == load_owner)
list_del(&config_csdev->node);
}
+ raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
}
static void cscfg_remove_owned_csdev_features(struct coresight_device *csdev, void *load_owner)
@@ -867,6 +870,28 @@ 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, bool enable)
+{
+ if (enable)
+ return atomic_inc_not_zero(&config_desc->active_cnt);
+
+ /* when activate config */
+
+ /* must ensure that config cannot be unloaded in use */
+ if (cscfg_owner_get(config_desc->load_owner))
+ return false;
+
+ atomic_inc(&config_desc->active_cnt);
+
+ 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.
@@ -890,22 +915,17 @@ 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, false)) {
+ 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;
@@ -920,9 +940,8 @@ 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;
}
@@ -1047,7 +1066,7 @@ 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;
@@ -1062,8 +1081,8 @@ 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, true)) {
config_csdev_active = config_csdev_item;
csdev->active_cscfg_ctxt = (void *)config_csdev_active;
break;
@@ -1097,7 +1116,11 @@ 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);
@@ -1136,8 +1159,10 @@ 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}
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