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coresight: prevent deactivate active config while enabling the config

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[ Upstream commit 408c97c4a5e0b634dcd15bf8b8808b382e888164 ]

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.

Fixes: f8cce2ff3c ("coresight: syscfg: Add API to activate and enable configurations")
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250514161951.3427590-4-yeoreum.yun@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Yeoreum Yun
2025-05-14 17:19:51 +01:00
committed by Greg Kroah-Hartman
parent e69e2cfd8b
commit b3b4efa2e6
2 changed files with 35 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/hwtracing/coresight/coresight-config.h
View File

@@ -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;

49
drivers/hwtracing/coresight/coresight-syscfg.c
View File

@@ -867,6 +867,25 @@ unlock_exit:
}
EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
static bool cscfg_config_desc_get(struct cscfg_config_desc *config_desc)
{
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.
@@ -890,22 +909,17 @@ 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;
@@ -920,9 +934,8 @@ 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 +1060,7 @@ 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 +1075,8 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
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;
@@ -1097,7 +1110,11 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
err = -EBUSY;
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 +1153,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
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);