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Date: Sat, 8 Jan 2022 13:25:12 +0530
From: Vijayanand@...eaurora.org, Jitta@...eaurora.org
To: joro@...tes.org, will@...nel.org, iommu@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org
Cc: kernel-team@...roid.com, vjitta@...eaurora.org,
Vijayanand Jitta <quic_vjitta@...cinc.com>
Subject: [PATCH v2] iommu: Fix potential use-after-free during probe
From: Vijayanand Jitta <quic_vjitta@...cinc.com>
Kasan has reported the following use after free on dev->iommu.
when a device probe fails and it is in process of freeing dev->iommu
in dev_iommu_free function, a deferred_probe_work_func runs in parallel
and tries to access dev->iommu->fwspec in of_iommu_configure path thus
causing use after free.
BUG: KASAN: use-after-free in of_iommu_configure+0xb4/0x4a4
Read of size 8 at addr ffffff87a2f1acb8 by task kworker/u16:2/153
Workqueue: events_unbound deferred_probe_work_func
Call trace:
dump_backtrace+0x0/0x33c
show_stack+0x18/0x24
dump_stack_lvl+0x16c/0x1e0
print_address_description+0x84/0x39c
__kasan_report+0x184/0x308
kasan_report+0x50/0x78
__asan_load8+0xc0/0xc4
of_iommu_configure+0xb4/0x4a4
of_dma_configure_id+0x2fc/0x4d4
platform_dma_configure+0x40/0x5c
really_probe+0x1b4/0xb74
driver_probe_device+0x11c/0x228
__device_attach_driver+0x14c/0x304
bus_for_each_drv+0x124/0x1b0
__device_attach+0x25c/0x334
device_initial_probe+0x24/0x34
bus_probe_device+0x78/0x134
deferred_probe_work_func+0x130/0x1a8
process_one_work+0x4c8/0x970
worker_thread+0x5c8/0xaec
kthread+0x1f8/0x220
ret_from_fork+0x10/0x18
Allocated by task 1:
____kasan_kmalloc+0xd4/0x114
__kasan_kmalloc+0x10/0x1c
kmem_cache_alloc_trace+0xe4/0x3d4
__iommu_probe_device+0x90/0x394
probe_iommu_group+0x70/0x9c
bus_for_each_dev+0x11c/0x19c
bus_iommu_probe+0xb8/0x7d4
bus_set_iommu+0xcc/0x13c
arm_smmu_bus_init+0x44/0x130 [arm_smmu]
arm_smmu_device_probe+0xb88/0xc54 [arm_smmu]
platform_drv_probe+0xe4/0x13c
really_probe+0x2c8/0xb74
driver_probe_device+0x11c/0x228
device_driver_attach+0xf0/0x16c
__driver_attach+0x80/0x320
bus_for_each_dev+0x11c/0x19c
driver_attach+0x38/0x48
bus_add_driver+0x1dc/0x3a4
driver_register+0x18c/0x244
__platform_driver_register+0x88/0x9c
init_module+0x64/0xff4 [arm_smmu]
do_one_initcall+0x17c/0x2f0
do_init_module+0xe8/0x378
load_module+0x3f80/0x4a40
__se_sys_finit_module+0x1a0/0x1e4
__arm64_sys_finit_module+0x44/0x58
el0_svc_common+0x100/0x264
do_el0_svc+0x38/0xa4
el0_svc+0x20/0x30
el0_sync_handler+0x68/0xac
el0_sync+0x160/0x180
Freed by task 1:
kasan_set_track+0x4c/0x84
kasan_set_free_info+0x28/0x4c
____kasan_slab_free+0x120/0x15c
__kasan_slab_free+0x18/0x28
slab_free_freelist_hook+0x204/0x2fc
kfree+0xfc/0x3a4
__iommu_probe_device+0x284/0x394
probe_iommu_group+0x70/0x9c
bus_for_each_dev+0x11c/0x19c
bus_iommu_probe+0xb8/0x7d4
bus_set_iommu+0xcc/0x13c
arm_smmu_bus_init+0x44/0x130 [arm_smmu]
arm_smmu_device_probe+0xb88/0xc54 [arm_smmu]
platform_drv_probe+0xe4/0x13c
really_probe+0x2c8/0xb74
driver_probe_device+0x11c/0x228
device_driver_attach+0xf0/0x16c
__driver_attach+0x80/0x320
bus_for_each_dev+0x11c/0x19c
driver_attach+0x38/0x48
bus_add_driver+0x1dc/0x3a4
driver_register+0x18c/0x244
__platform_driver_register+0x88/0x9c
init_module+0x64/0xff4 [arm_smmu]
do_one_initcall+0x17c/0x2f0
do_init_module+0xe8/0x378
load_module+0x3f80/0x4a40
__se_sys_finit_module+0x1a0/0x1e4
__arm64_sys_finit_module+0x44/0x58
el0_svc_common+0x100/0x264
do_el0_svc+0x38/0xa4
el0_svc+0x20/0x30
el0_sync_handler+0x68/0xac
el0_sync+0x160/0x180
Fix this by adding device_lock for dev->iommu accesses.
Signed-off-by: Vijayanand Jitta <quic_vjitta@...cinc.com>
---
drivers/iommu/iommu.c | 9 +++++++++
include/linux/iommu.h | 32 ++++++++++++++++++++++++++------
2 files changed, 35 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d410311..c5f35c5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -171,6 +171,7 @@ EXPORT_SYMBOL_GPL(iommu_device_unregister);
static struct dev_iommu *dev_iommu_get(struct device *dev)
{
struct dev_iommu *param = dev->iommu;
+ int ret;
if (param)
return param;
@@ -180,15 +181,23 @@ static struct dev_iommu *dev_iommu_get(struct device *dev)
return NULL;
mutex_init(¶m->lock);
+ ret = device_trylock(dev);
dev->iommu = param;
+ if (ret)
+ device_unlock(dev);
return param;
}
static void dev_iommu_free(struct device *dev)
{
+ int ret;
+
iommu_fwspec_free(dev);
+ ret = device_trylock(dev);
kfree(dev->iommu);
dev->iommu = NULL;
+ if (ret)
+ device_unlock(dev);
}
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index f7f6ada..2edd624 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -627,29 +627,49 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode);
static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
{
+ struct iommu_fwspec *fwspec = NULL;
+ int ret;
+
+ ret = device_trylock(dev);
if (dev->iommu)
- return dev->iommu->fwspec;
- else
- return NULL;
+ fwspec = dev->iommu->fwspec;
+ if (ret)
+ device_unlock(dev);
+ return fwspec;
}
static inline void dev_iommu_fwspec_set(struct device *dev,
struct iommu_fwspec *fwspec)
{
+ int ret;
+
+ ret = device_trylock(dev);
dev->iommu->fwspec = fwspec;
+ if (ret)
+ device_unlock(dev);
}
static inline void *dev_iommu_priv_get(struct device *dev)
{
+ int ret;
+ void *priv = NULL;
+
+ ret = device_trylock(dev);
if (dev->iommu)
- return dev->iommu->priv;
- else
- return NULL;
+ priv = dev->iommu->priv;
+ if (ret)
+ device_unlock(dev);
+ return priv;
}
static inline void dev_iommu_priv_set(struct device *dev, void *priv)
{
+ int ret;
+
+ ret = device_trylock(dev);
dev->iommu->priv = priv;
+ if (ret)
+ device_unlock(dev);
}
int iommu_probe_device(struct device *dev);
--
2.7.4
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