Bug 2396530 (CVE-2022-50412)

Summary: CVE-2022-50412 kernel: drm: bridge: adv7511: unregister cec i2c device after cec adapter
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2025-09-18 17:03:37 UTC
In the Linux kernel, the following vulnerability has been resolved:

drm: bridge: adv7511: unregister cec i2c device after cec adapter

cec_unregister_adapter() assumes that the underlying adapter ops are
callable. For example, if the CEC adapter currently has a valid physical
address, then the unregistration procedure will invalidate the physical
address by setting it to f.f.f.f. Whence the following kernel oops
observed after removing the adv7511 module:

    Unable to handle kernel execution of user memory at virtual address 0000000000000000
    Internal error: Oops: 86000004 [#1] PREEMPT_RT SMP
    Call trace:
     0x0
     adv7511_cec_adap_log_addr+0x1ac/0x1c8 [adv7511]
     cec_adap_unconfigure+0x44/0x90 [cec]
     __cec_s_phys_addr.part.0+0x68/0x230 [cec]
     __cec_s_phys_addr+0x40/0x50 [cec]
     cec_unregister_adapter+0xb4/0x118 [cec]
     adv7511_remove+0x60/0x90 [adv7511]
     i2c_device_remove+0x34/0xe0
     device_release_driver_internal+0x114/0x1f0
     driver_detach+0x54/0xe0
     bus_remove_driver+0x60/0xd8
     driver_unregister+0x34/0x60
     i2c_del_driver+0x2c/0x68
     adv7511_exit+0x1c/0x67c [adv7511]
     __arm64_sys_delete_module+0x154/0x288
     invoke_syscall+0x48/0x100
     el0_svc_common.constprop.0+0x48/0xe8
     do_el0_svc+0x28/0x88
     el0_svc+0x1c/0x50
     el0t_64_sync_handler+0xa8/0xb0
     el0t_64_sync+0x15c/0x160
    Code: bad PC value
    ---[ end trace 0000000000000000 ]---

Protect against this scenario by unregistering i2c_cec after
unregistering the CEC adapter. Duly disable the CEC clock afterwards
too.