From a2e7e59a94269484a83386972ca07c22fd188854 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Wed, 15 Nov 2023 18:25:44 +0000 Subject: iommu: Avoid more races around device probe MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It turns out there are more subtle races beyond just the main part of __iommu_probe_device() itself running in parallel - the dev_iommu_free() on the way out of an unsuccessful probe can still manage to trip up concurrent accesses to a device's fwspec. Thus, extend the scope of iommu_probe_device_lock() to also serialise fwspec creation and initial retrieval. Reported-by: Zhenhua Huang Link: https://lore.kernel.org/linux-iommu/e2e20e1c-6450-4ac5-9804-b0000acdf7de@quicinc.com/ Fixes: 01657bc14a39 ("iommu: Avoid races around device probe") Signed-off-by: Robin Murphy Acked-by: Greg Kroah-Hartman Reviewed-by: André Draszik Tested-by: André Draszik Link: https://lore.kernel.org/r/16f433658661d7cadfea51e7c65da95826112a2b.1700071477.git.robin.murphy@arm.com Cc: stable@vger.kernel.org Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 20 ++++++++++---------- drivers/iommu/of_iommu.c | 12 +++++++++--- 2 files changed, 19 insertions(+), 13 deletions(-) (limited to 'drivers/iommu') diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index c9a05bb49bfa..33e2a9b5d339 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -485,11 +485,12 @@ static void iommu_deinit_device(struct device *dev) dev_iommu_free(dev); } +DEFINE_MUTEX(iommu_probe_device_lock); + static int __iommu_probe_device(struct device *dev, struct list_head *group_list) { const struct iommu_ops *ops = dev->bus->iommu_ops; struct iommu_group *group; - static DEFINE_MUTEX(iommu_probe_device_lock); struct group_device *gdev; int ret; @@ -502,17 +503,15 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list * probably be able to use device_lock() here to minimise the scope, * but for now enforcing a simple global ordering is fine. */ - mutex_lock(&iommu_probe_device_lock); + lockdep_assert_held(&iommu_probe_device_lock); /* Device is probed already if in a group */ - if (dev->iommu_group) { - ret = 0; - goto out_unlock; - } + if (dev->iommu_group) + return 0; ret = iommu_init_device(dev, ops); if (ret) - goto out_unlock; + return ret; group = dev->iommu_group; gdev = iommu_group_alloc_device(group, dev); @@ -548,7 +547,6 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list list_add_tail(&group->entry, group_list); } mutex_unlock(&group->mutex); - mutex_unlock(&iommu_probe_device_lock); if (dev_is_pci(dev)) iommu_dma_set_pci_32bit_workaround(dev); @@ -562,8 +560,6 @@ err_put_group: iommu_deinit_device(dev); mutex_unlock(&group->mutex); iommu_group_put(group); -out_unlock: - mutex_unlock(&iommu_probe_device_lock); return ret; } @@ -573,7 +569,9 @@ int iommu_probe_device(struct device *dev) const struct iommu_ops *ops; int ret; + mutex_lock(&iommu_probe_device_lock); ret = __iommu_probe_device(dev, NULL); + mutex_unlock(&iommu_probe_device_lock); if (ret) return ret; @@ -1822,7 +1820,9 @@ static int probe_iommu_group(struct device *dev, void *data) struct list_head *group_list = data; int ret; + mutex_lock(&iommu_probe_device_lock); ret = __iommu_probe_device(dev, group_list); + mutex_unlock(&iommu_probe_device_lock); if (ret == -ENODEV) ret = 0; diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c index 157b286e36bf..c25b4ae6aeee 100644 --- a/drivers/iommu/of_iommu.c +++ b/drivers/iommu/of_iommu.c @@ -112,16 +112,20 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, const u32 *id) { const struct iommu_ops *ops = NULL; - struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); + struct iommu_fwspec *fwspec; int err = NO_IOMMU; if (!master_np) return NULL; + /* Serialise to make dev->iommu stable under our potential fwspec */ + mutex_lock(&iommu_probe_device_lock); + fwspec = dev_iommu_fwspec_get(dev); if (fwspec) { - if (fwspec->ops) + if (fwspec->ops) { + mutex_unlock(&iommu_probe_device_lock); return fwspec->ops; - + } /* In the deferred case, start again from scratch */ iommu_fwspec_free(dev); } @@ -155,6 +159,8 @@ const struct iommu_ops *of_iommu_configure(struct device *dev, fwspec = dev_iommu_fwspec_get(dev); ops = fwspec->ops; } + mutex_unlock(&iommu_probe_device_lock); + /* * If we have reason to believe the IOMMU driver missed the initial * probe for dev, replay it to get things in order. -- cgit v1.2.3