Subject: CVE-2022-48796: iommu: Fix potential use-after-free during probe

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

iommu: Fix potential use-after-free during probe

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 setting dev->iommu to NULL first and
then freeing dev_iommu structure in dev_iommu_free
function.

The Linux kernel CVE team has assigned CVE-2022-48796 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.10.101 with commit cb86e511e78e
	Fixed in 5.15.24 with commit 65ab30f6a695
	Fixed in 5.16.10 with commit f74fc4b5bd53
	Fixed in 5.17 with commit b54240ad4943

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48796
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/iommu/iommu.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/cb86e511e78e796de6947b8f3acca1b7c76fb2ff
	https://git.kernel.org/stable/c/65ab30f6a6952fa9ee13009862736cf8d110e6e5
	https://git.kernel.org/stable/c/f74fc4b5bd533ea3d30ce47cccb8ef8d21fda85a
	https://git.kernel.org/stable/c/b54240ad494300ff0994c4539a531727874381f4