Messages in this thread Patch in this message | | | From | , | Subject | [PATCH] iommu: Fix potential use-after-free during probe | Date | Fri, 7 Jan 2022 18:11:06 +0530 |
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From: Vijayanand Jitta <quic_vjitta@quicinc.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@quicinc.com> --- drivers/iommu/iommu.c | 4 ++++ include/linux/iommu.h | 22 ++++++++++++++++------ 2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index dd7863e..85a2caa 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -201,15 +201,19 @@ static struct dev_iommu *dev_iommu_get(struct device *dev) return NULL; mutex_init(¶m->lock); + device_lock(dev); dev->iommu = param; + device_unlock(dev); return param; } static void dev_iommu_free(struct device *dev) { iommu_fwspec_free(dev); + device_lock(dev); kfree(dev->iommu); dev->iommu = NULL; + 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 d2f3435..01b09be 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -640,29 +640,39 @@ 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; + + device_lock(dev); if (dev->iommu) - return dev->iommu->fwspec; - else - return NULL; + fwspec = dev->iommu->fwspec; + device_unlock(dev); + return fwspec; } static inline void dev_iommu_fwspec_set(struct device *dev, struct iommu_fwspec *fwspec) { + device_lock(dev); dev->iommu->fwspec = fwspec; + device_unlock(dev); } static inline void *dev_iommu_priv_get(struct device *dev) { + void *priv = NULL; + + device_lock(dev); if (dev->iommu) - return dev->iommu->priv; - else - return NULL; + priv = dev->iommu->priv; + device_unlock(dev); + return priv; } static inline void dev_iommu_priv_set(struct device *dev, void *priv) { + device_lock(dev); dev->iommu->priv = priv; + device_unlock(dev); } int iommu_probe_device(struct device *dev); -- 2.7.4
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