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specifically in of_phy_get() if it was possible between > returning from _of_phy_get() and running try_module_get() that a module > might be unbound leading to use-after-free. > > Looking at the code this appears to be so, there is no linkage between the > phy and module under a synchronisation primitive. > > Using the phy_provider_mutex in phy_get() will ensure there is a link between > the returned phy pointer and the module_get() bumping the module reference > count. > > Amend phy_get(), of_phy_get() and devm_of_phy_get_by_index() to fix the > same usage pattern. > > phy_provider_unregister() must take the phy_provider_mutex so amending > phy_get()/of_phy_get() to take that same mutex guarantees there is no > use-after-free. > > Fixes: ff764963479a1 ("drivers: phy: add generic PHY framework") > Cc: stable@vger.kernel.org > Reviewed-by: Loic Poulain > Signed-off-by: Bryan O'Donoghue > --- ... > > @@ -678,15 +677,21 @@ struct phy *of_phy_get(struct device_node *np, const char *con_id) > if (con_id) > index = of_property_match_string(np, "phy-names", con_id); > > + mutex_lock(&phy_provider_mutex); > + > phy = _of_phy_get(np, index); > if (IS_ERR(phy)) > - return phy; > + goto out_unlock; > > - if (!try_module_get(phy->ops->owner)) > - return ERR_PTR(-EPROBE_DEFER); > + if (!try_module_get(phy->ops->owner)) { > + phy = ERR_PTR(-EPROBE_DEFER); > + goto out_unlock; > + } why no use auto cleanup guard() for mutex lock? Frank > > get_device(&phy->dev); > > +out_unlock: > + mutex_unlock(&phy_provider_mutex); > return phy; > } > EXPORT_SYMBOL_GPL(of_phy_get); > @@ -786,6 +791,7 @@ struct phy *phy_get(struct device *dev, const char *string) > struct phy *phy; > struct device_link *link; > > + mutex_lock(&phy_provider_mutex); > if (dev->of_node) { > if (string) > index = of_property_match_string(dev->of_node, "phy-names", > @@ -796,15 +802,18 @@ struct phy *phy_get(struct device *dev, const char *string) > } else { > if (string == NULL) { > dev_WARN(dev, "missing string\n"); > - return ERR_PTR(-EINVAL); > + phy = ERR_PTR(-EINVAL); > + goto out_unlock; > } > phy = phy_find(dev, string); > } > if (IS_ERR(phy)) > - return phy; > + goto out_unlock; > > - if (!try_module_get(phy->ops->owner)) > - return ERR_PTR(-EPROBE_DEFER); > + if (!try_module_get(phy->ops->owner)) { > + phy = ERR_PTR(-EPROBE_DEFER); > + goto out_unlock; > + } > > get_device(&phy->dev); > > @@ -813,6 +822,8 @@ struct phy *phy_get(struct device *dev, const char *string) > dev_dbg(dev, "failed to create device link to %s\n", > dev_name(phy->dev.parent)); > > +out_unlock: > + mutex_unlock(&phy_provider_mutex); > return phy; > } > EXPORT_SYMBOL_GPL(phy_get); > @@ -961,15 +972,17 @@ struct phy *devm_of_phy_get_by_index(struct device *dev, struct device_node *np, > if (!ptr) > return ERR_PTR(-ENOMEM); > > + mutex_lock(&phy_provider_mutex); > phy = _of_phy_get(np, index); > if (IS_ERR(phy)) { > devres_free(ptr); > - return phy; > + goto out_unlock; > } > > if (!try_module_get(phy->ops->owner)) { > devres_free(ptr); > - return ERR_PTR(-EPROBE_DEFER); > + phy = ERR_PTR(-EPROBE_DEFER); > + goto out_unlock; > } > > get_device(&phy->dev); > @@ -982,6 +995,8 @@ struct phy *devm_of_phy_get_by_index(struct device *dev, struct device_node *np, > dev_dbg(dev, "failed to create device link to %s\n", > dev_name(phy->dev.parent)); > > +out_unlock: > + mutex_unlock(&phy_provider_mutex); > return phy; > } > EXPORT_SYMBOL_GPL(devm_of_phy_get_by_index); > > -- > 2.55.0 >