@@ -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;
@@ -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();
/*
@@ -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);
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@arm.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(-) -- LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}