The PSE PI regulators are devm-registered inside pse_controller_register(), which runs before devres_add() arms the controller's own release in devm_pse_controller_register(). On driver detach devres unwinds in LIFO order, so pse_controller_unregister() runs first and frees pcdev->pi via pse_release_pis(); the regulators are torn down afterwards. When regulator_unregister() flushes a pending disable, the regulator core invokes pse_pi_disable(), which dereferences pcdev->pi[id] (directly and via _pse_pi_disable() -> pse_pi_deallocate_pw_budget()). At that point the PI array is already freed, so this is a use-after-free. pse_pi_enable() and pse_pi_is_enabled() dereference pcdev->pi[id] the same way and are reachable by any regulator consumer that keeps a handle across the teardown window. Clear pcdev->pi after freeing it and bail out of the three regulator ops that dereference it when it is NULL. Perform the kfree() and NULL store in pse_release_pis() under pcdev->lock, and read pcdev->pi under the same lock in the ops, so the NULL an op observes is authoritative even when the free runs concurrently on another CPU: the op either sees the live array or returns without touching freed memory. The other three regulator ops (pse_pi_get_voltage(), pse_pi_get_current_limit(), pse_pi_set_current_limit()) do not dereference pcdev->pi and need no guard. Fixes: ffef61d6d273 ("net: pse-pd: Add support for budget evaluation strategies") Signed-off-by: Carlo Szelinsky Reviewed-by: Kory Maincent --- drivers/net/pse-pd/pse_core.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/net/pse-pd/pse_core.c b/drivers/net/pse-pd/pse_core.c index 6045b6c399c2..21ccb5146616 100644 --- a/drivers/net/pse-pd/pse_core.c +++ b/drivers/net/pse-pd/pse_core.c @@ -144,7 +144,13 @@ static void pse_release_pis(struct pse_controller_dev *pcdev) of_node_put(pcdev->pi[i].pairset[1].np); of_node_put(pcdev->pi[i].np); } + /* Free under the lock so the NULL store is authoritative against + * the regulator ops that read pcdev->pi under pcdev->lock. + */ + mutex_lock(&pcdev->lock); kfree(pcdev->pi); + pcdev->pi = NULL; + mutex_unlock(&pcdev->lock); } /** @@ -421,6 +427,11 @@ static int pse_pi_is_enabled(struct regulator_dev *rdev) id = rdev_get_id(rdev); mutex_lock(&pcdev->lock); + /* Controller may be unregistered (pcdev->pi freed) mid-teardown. */ + if (!pcdev->pi) { + ret = -ENODEV; + goto out; + } if (pse_pw_d_is_sw_pw_control(pcdev, pcdev->pi[id].pw_d)) { ret = pcdev->pi[id].admin_state_enabled; goto out; @@ -674,6 +685,11 @@ static int pse_pi_enable(struct regulator_dev *rdev) id = rdev_get_id(rdev); mutex_lock(&pcdev->lock); + /* Controller may be unregistered (pcdev->pi freed) mid-teardown. */ + if (!pcdev->pi) { + mutex_unlock(&pcdev->lock); + return -ENODEV; + } if (pse_pw_d_is_sw_pw_control(pcdev, pcdev->pi[id].pw_d)) { /* Manage enabled status by software. * Real enable process will happen if a port is connected. @@ -702,15 +718,20 @@ static int pse_pi_enable(struct regulator_dev *rdev) static int pse_pi_disable(struct regulator_dev *rdev) { struct pse_controller_dev *pcdev = rdev_get_drvdata(rdev); - struct pse_pi *pi; int id, ret; id = rdev_get_id(rdev); - pi = &pcdev->pi[id]; mutex_lock(&pcdev->lock); + /* Reached via the regulator core's deferred-disable flush after + * pcdev->pi is freed on unregister. + */ + if (!pcdev->pi) { + mutex_unlock(&pcdev->lock); + return 0; + } ret = _pse_pi_disable(pcdev, id); if (!ret) - pi->admin_state_enabled = 0; + pcdev->pi[id].admin_state_enabled = 0; mutex_unlock(&pcdev->lock); return 0; -- 2.43.0