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 yeoreum.yun@arm.com
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