From 797a8b4d768c58caac58ee3e8cb36a164d1b7751 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Mon, 16 Jan 2017 12:58:07 +0000 Subject: [PATCH] iommu: Handle default domain attach failure We wouldn't normally expect ops->attach_dev() to fail, but on IOMMUs with limited hardware resources, or generally misconfigured systems, it is certainly possible. We report failure correctly from the external iommu_attach_device() interface, but do not do so in iommu_group_add() when attaching to the default domain. The result of failure there is that the device, group and domain all get left in a broken, part-configured state which leads to weird errors and misbehaviour down the line when IOMMU API calls sort-of-but-don't-quite work. Check the return value of __iommu_attach_device() on the default domain, and refactor the error handling paths to cope with its failure and clean up correctly in such cases. Fixes: e39cb8a3aa98 ("iommu: Make sure a device is always attached to a domain") Reported-by: Punit Agrawal Signed-off-by: Robin Murphy Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index dbe7f653bb7c..aed906a3e3db 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -383,36 +383,30 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) device->dev = dev; ret = sysfs_create_link(&dev->kobj, &group->kobj, "iommu_group"); - if (ret) { - kfree(device); - return ret; - } + if (ret) + goto err_free_device; device->name = kasprintf(GFP_KERNEL, "%s", kobject_name(&dev->kobj)); rename: if (!device->name) { - sysfs_remove_link(&dev->kobj, "iommu_group"); - kfree(device); - return -ENOMEM; + ret = -ENOMEM; + goto err_remove_link; } ret = sysfs_create_link_nowarn(group->devices_kobj, &dev->kobj, device->name); if (ret) { - kfree(device->name); if (ret == -EEXIST && i >= 0) { /* * Account for the slim chance of collision * and append an instance to the name. */ + kfree(device->name); device->name = kasprintf(GFP_KERNEL, "%s.%d", kobject_name(&dev->kobj), i++); goto rename; } - - sysfs_remove_link(&dev->kobj, "iommu_group"); - kfree(device); - return ret; + goto err_free_name; } kobject_get(group->devices_kobj); @@ -424,8 +418,10 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) mutex_lock(&group->mutex); list_add_tail(&device->list, &group->devices); if (group->domain) - __iommu_attach_device(group->domain, dev); + ret = __iommu_attach_device(group->domain, dev); mutex_unlock(&group->mutex); + if (ret) + goto err_put_group; /* Notify any listeners about change to group. */ blocking_notifier_call_chain(&group->notifier, @@ -436,6 +432,21 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev) pr_info("Adding device %s to group %d\n", dev_name(dev), group->id); return 0; + +err_put_group: + mutex_lock(&group->mutex); + list_del(&device->list); + mutex_unlock(&group->mutex); + dev->iommu_group = NULL; + kobject_put(group->devices_kobj); +err_free_name: + kfree(device->name); +err_remove_link: + sysfs_remove_link(&dev->kobj, "iommu_group"); +err_free_device: + kfree(device); + pr_err("Failed to add device %s to group %d: %d\n", dev_name(dev), group->id, ret); + return ret; } EXPORT_SYMBOL_GPL(iommu_group_add_device);