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authorRob Herring <robh@kernel.org>2020-05-13 17:38:59 -0500
committerBjorn Helgaas <bhelgaas@google.com>2020-05-14 16:36:35 -0500
commit9885440b16b8fc1dd7275800fd28f56a92f60896 (patch)
treed9d0b84f87a9a1271b03cabc7217e713b55fe104 /drivers/pci/probe.c
parent1b54ae8327a4d630111c8d88ba7906483ec6010b (diff)
downloadlinux-9885440b16b8fc1dd7275800fd28f56a92f60896.tar.bz2
PCI: Fix pci_host_bridge struct device release/free handling
The PCI code has several paths where the struct pci_host_bridge is freed directly. This is wrong because it contains a struct device which is refcounted and should be freed using put_device(). This can result in use-after-free errors. I think this problem has existed since 2012 with commit 7b5436635800 ("PCI: add generic device into pci_host_bridge struct"). It generally hasn't mattered as most host bridge drivers are still built-in and can't unbind. The problem is a struct device should never be freed directly once device_initialize() is called and a ref is held, but that doesn't happen until pci_register_host_bridge(). There's then a window between allocating the host bridge and pci_register_host_bridge() where kfree should be used. This is fragile and requires callers to do the right thing. To fix this, we need to split device_register() into device_initialize() and device_add() calls, so that the host bridge struct is always freed by using a put_device(). devm_pci_alloc_host_bridge() is using devm_kzalloc() to allocate struct pci_host_bridge which will be freed directly. Instead, we can use a custom devres action to call put_device(). Link: https://lore.kernel.org/r/20200513223859.11295-2-robh@kernel.org Reported-by: Anders Roxell <anders.roxell@linaro.org> Tested-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Rob Herring <robh@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'drivers/pci/probe.c')
-rw-r--r--drivers/pci/probe.c36
1 files changed, 19 insertions, 17 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e21dc71b1907..e064ded6fbec 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -565,7 +565,7 @@ static struct pci_bus *pci_alloc_bus(struct pci_bus *parent)
return b;
}
-static void devm_pci_release_host_bridge_dev(struct device *dev)
+static void pci_release_host_bridge_dev(struct device *dev)
{
struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
@@ -574,12 +574,7 @@ static void devm_pci_release_host_bridge_dev(struct device *dev)
pci_free_resource_list(&bridge->windows);
pci_free_resource_list(&bridge->dma_ranges);
-}
-
-static void pci_release_host_bridge_dev(struct device *dev)
-{
- devm_pci_release_host_bridge_dev(dev);
- kfree(to_pci_host_bridge(dev));
+ kfree(bridge);
}
static void pci_init_host_bridge(struct pci_host_bridge *bridge)
@@ -599,6 +594,8 @@ static void pci_init_host_bridge(struct pci_host_bridge *bridge)
bridge->native_pme = 1;
bridge->native_ltr = 1;
bridge->native_dpc = 1;
+
+ device_initialize(&bridge->dev);
}
struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
@@ -616,17 +613,25 @@ struct pci_host_bridge *pci_alloc_host_bridge(size_t priv)
}
EXPORT_SYMBOL(pci_alloc_host_bridge);
+static void devm_pci_alloc_host_bridge_release(void *data)
+{
+ pci_free_host_bridge(data);
+}
+
struct pci_host_bridge *devm_pci_alloc_host_bridge(struct device *dev,
size_t priv)
{
+ int ret;
struct pci_host_bridge *bridge;
- bridge = devm_kzalloc(dev, sizeof(*bridge) + priv, GFP_KERNEL);
+ bridge = pci_alloc_host_bridge(priv);
if (!bridge)
return NULL;
- pci_init_host_bridge(bridge);
- bridge->dev.release = devm_pci_release_host_bridge_dev;
+ ret = devm_add_action_or_reset(dev, devm_pci_alloc_host_bridge_release,
+ bridge);
+ if (ret)
+ return NULL;
return bridge;
}
@@ -634,10 +639,7 @@ EXPORT_SYMBOL(devm_pci_alloc_host_bridge);
void pci_free_host_bridge(struct pci_host_bridge *bridge)
{
- pci_free_resource_list(&bridge->windows);
- pci_free_resource_list(&bridge->dma_ranges);
-
- kfree(bridge);
+ put_device(&bridge->dev);
}
EXPORT_SYMBOL(pci_free_host_bridge);
@@ -908,7 +910,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
if (err)
goto free;
- err = device_register(&bridge->dev);
+ err = device_add(&bridge->dev);
if (err) {
put_device(&bridge->dev);
goto free;
@@ -978,7 +980,7 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
unregister:
put_device(&bridge->dev);
- device_unregister(&bridge->dev);
+ device_del(&bridge->dev);
free:
kfree(bus);
@@ -2953,7 +2955,7 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
return bridge->bus;
err_out:
- kfree(bridge);
+ put_device(&bridge->dev);
return NULL;
}
EXPORT_SYMBOL_GPL(pci_create_root_bus);