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    Subject[PATCH AUTOSEL 5.15 19/36] iommu: Fix potential use-after-free during probe
    Date
    From: Vijayanand Jitta <quic_vjitta@quicinc.com>

    [ Upstream commit b54240ad494300ff0994c4539a531727874381f4 ]

    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.

    Suggested-by: Robin Murphy <robin.murphy@arm.com>
    Signed-off-by: Vijayanand Jitta <quic_vjitta@quicinc.com>
    Link: https://lore.kernel.org/r/1643613155-20215-1-git-send-email-quic_vjitta@quicinc.com
    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/iommu/iommu.c | 9 +++++++--
    1 file changed, 7 insertions(+), 2 deletions(-)

    diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
    index f62fb6a58f109..7f409e9eea4b7 100644
    --- a/drivers/iommu/iommu.c
    +++ b/drivers/iommu/iommu.c
    @@ -206,9 +206,14 @@ static struct dev_iommu *dev_iommu_get(struct device *dev)

    static void dev_iommu_free(struct device *dev)
    {
    - iommu_fwspec_free(dev);
    - kfree(dev->iommu);
    + struct dev_iommu *param = dev->iommu;
    +
    dev->iommu = NULL;
    + if (param->fwspec) {
    + fwnode_handle_put(param->fwspec->iommu_fwnode);
    + kfree(param->fwspec);
    + }
    + kfree(param);
    }

    static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
    --
    2.34.1
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