| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <aCR7Jr0RCWvqb0iM@e129823.arm.com>
Date: Wed, 14 May 2025 12:14:46 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: Leo Yan <leo.yan@....com>
Cc: mike.leach@...aro.org, james.clark@...aro.org,
alexander.shishkin@...ux.intel.com, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] coresight: prevent deactivate active config while
enabling the config
Hi Leo,
> 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@....com>
>
> And please add a fix tag:
>
> Fixes: f8cce2ff3c04 ("coresight: syscfg: Add API to activate and enable configurations")
Sorry to annoying you. Thanks ;)
>
> > > ---
> > > .../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@...ts.linaro.org
> > To unsubscribe send an email to coresight-leave@...ts.linaro.org
--
Sincerely,
Yeoreum Yun
Powered by blists - more mailing lists