• Wu Bo's avatar
    ipmi: Fix UAF when uninstall ipmi_si and ipmi_msghandler module · ffb76a86
    Wu Bo authored
    Hi,
    
    When testing install and uninstall of ipmi_si.ko and ipmi_msghandler.ko,
    the system crashed.
    
    The log as follows:
    [  141.087026] BUG: unable to handle kernel paging request at ffffffffc09b3a5a
    [  141.087241] PGD 8fe4c0d067 P4D 8fe4c0d067 PUD 8fe4c0f067 PMD 103ad89067 PTE 0
    [  141.087464] Oops: 0010 [#1] SMP NOPTI
    [  141.087580] CPU: 67 PID: 668 Comm: kworker/67:1 Kdump: loaded Not tainted 4.18.0.x86_64 #47
    [  141.088009] Workqueue: events 0xffffffffc09b3a40
    [  141.088009] RIP: 0010:0xffffffffc09b3a5a
    [  141.088009] Code: Bad RIP value.
    [  141.088009] RSP: 0018:ffffb9094e2c3e88 EFLAGS: 00010246
    [  141.088009] RAX: 0000000000000000 RBX: ffff9abfdb1f04a0 RCX: 0000000000000000
    [  141.088009] RDX: 0000000000000000 RSI: 0000000000000246 RDI: 0000000000000246
    [  141.088009] RBP: 0000000000000000 R08: ffff9abfffee3cb8 R09: 00000000000002e1
    [  141.088009] R10: ffffb9094cb73d90 R11: 00000000000f4240 R12: ffff9abfffee8700
    [  141.088009] R13: 0000000000000000 R14: ffff9abfdb1f04a0 R15: ffff9abfdb1f04a8
    [  141.088009] FS:  0000000000000000(0000) GS:ffff9abfffec0000(0000) knlGS:0000000000000000
    [  141.088009] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  141.088009] CR2: ffffffffc09b3a30 CR3: 0000008fe4c0a001 CR4: 00000000007606e0
    [  141.088009] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    [  141.088009] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    [  141.088009] PKRU: 55555554
    [  141.088009] Call Trace:
    [  141.088009]  ? process_one_work+0x195/0x390
    [  141.088009]  ? worker_thread+0x30/0x390
    [  141.088009]  ? process_one_work+0x390/0x390
    [  141.088009]  ? kthread+0x10d/0x130
    [  141.088009]  ? kthread_flush_work_fn+0x10/0x10
    [  141.088009]  ? ret_from_fork+0x35/0x40] BUG: unable to handle kernel paging request at ffffffffc0b28a5a
    [  200.223240] PGD 97fe00d067 P4D 97fe00d067 PUD 97fe00f067 PMD a580cbf067 PTE 0
    [  200.223464] Oops: 0010 [#1] SMP NOPTI
    [  200.223579] CPU: 63 PID: 664 Comm: kworker/63:1 Kdump: loaded Not tainted 4.18.0.x86_64 #46
    [  200.224008] Workqueue: events 0xffffffffc0b28a40
    [  200.224008] RIP: 0010:0xffffffffc0b28a5a
    [  200.224008] Code: Bad RIP value.
    [  200.224008] RSP: 0018:ffffbf3c8e2a3e88 EFLAGS: 00010246
    [  200.224008] RAX: 0000000000000000 RBX: ffffa0799ad6bca0 RCX: 0000000000000000
    [  200.224008] RDX: 0000000000000000 RSI: 0000000000000246 RDI: 0000000000000246
    [  200.224008] RBP: 0000000000000000 R08: ffff9fe43fde3cb8 R09: 00000000000000d5
    [  200.224008] R10: ffffbf3c8cb53d90 R11: 00000000000f4240 R12: ffff9fe43fde8700
    [  200.224008] R13: 0000000000000000 R14: ffffa0799ad6bca0 R15: ffffa0799ad6bca8
    [  200.224008] FS:  0000000000000000(0000) GS:ffff9fe43fdc0000(0000) knlGS:0000000000000000
    [  200.224008] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [  200.224008] CR2: ffffffffc0b28a30 CR3: 00000097fe00a002 CR4: 00000000007606e0
    [  200.224008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    [  200.224008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    [  200.224008] PKRU: 55555554
    [  200.224008] Call Trace:
    [  200.224008]  ? process_one_work+0x195/0x390
    [  200.224008]  ? worker_thread+0x30/0x390
    [  200.224008]  ? process_one_work+0x390/0x390
    [  200.224008]  ? kthread+0x10d/0x130
    [  200.224008]  ? kthread_flush_work_fn+0x10/0x10
    [  200.224008]  ? ret_from_fork+0x35/0x40
    [  200.224008] kernel fault(0x1) notification starting on CPU 63
    [  200.224008] kernel fault(0x1) notification finished on CPU 63
    [  200.224008] CR2: ffffffffc0b28a5a
    [  200.224008] ---[ end trace c82a412d93f57412 ]---
    
    The reason is as follows:
    T1: rmmod ipmi_si.
        ->ipmi_unregister_smi()
            -> ipmi_bmc_unregister()
                -> __ipmi_bmc_unregister()
                    -> kref_put(&bmc->usecount, cleanup_bmc_device);
                        -> schedule_work(&bmc->remove_work);
    
    T2: rmmod ipmi_msghandler.
        ipmi_msghander module uninstalled, and the module space
        will be freed.
    
    T3: bmc->remove_work doing cleanup the bmc resource.
        -> cleanup_bmc_work()
            -> platform_device_unregister(&bmc->pdev);
                -> platform_device_del(pdev);
                    -> device_del(&pdev->dev);
                        -> kobject_uevent(&dev->kobj, KOBJ_REMOVE);
                            -> kobject_uevent_env()
                                -> dev_uevent()
                                    -> if (dev->type && dev->type->name)
    
       'dev->type'(bmc_device_type) pointer space has freed when uninstall
        ipmi_msghander module, 'dev->type->name' cause the system crash.
    
    drivers/char/ipmi/ipmi_msghandler.c:
    2820 static const struct device_type bmc_device_type = {
    2821         .groups         = bmc_dev_attr_groups,
    2822 };
    
    Steps to reproduce:
    Add a time delay in cleanup_bmc_work() function,
    and uninstall ipmi_si and ipmi_msghandler module.
    
    2910 static void cleanup_bmc_work(struct work_struct *work)
    2911 {
    2912         struct bmc_device *bmc = container_of(work, struct bmc_device,
    2913                                               remove_work);
    2914         int id = bmc->pdev.id; /* Unregister overwrites id */
    2915
    2916         msleep(3000);   <---
    2917         platform_device_unregister(&bmc->pdev);
    2918         ida_simple_remove(&ipmi_bmc_ida, id);
    2919 }
    
    Use 'remove_work_wq' instead of 'system_wq' to solve this issues.
    
    Fixes: b2cfd8ab ("ipmi: Rework device id and guid handling to catch changing BMCs")
    Signed-off-by: default avatarWu Bo <wubo40@huawei.com>
    Message-Id: <1640070034-56671-1-git-send-email-wubo40@huawei.com>
    Signed-off-by: default avatarCorey Minyard <cminyard@mvista.com>
    ffb76a86
ipmi_msghandler.c 139 KB