CVE-2022-49823 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
ata: libata-transport: fix error handling in ata_tdev_add()
In ata_tdev_add(), the return value of transport_add_device() is not checked. As a result, it causes null-ptr-deref while removing the module, because transport_remove_device() is called to remove the device that was not added.
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000d0 CPU: 13 PID: 13603 Comm: rmmod Kdump: loaded Tainted: G W 6.1.0-rc3+ #36 pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : device_del+0x48/0x3a0 lr : device_del+0x44/0x3a0 Call trace: device_del+0x48/0x3a0 attribute_container_class_device_del+0x28/0x40 transport_remove_classdev+0x60/0x7c attribute_container_device_trigger+0x118/0x120 transport_remove_device+0x20/0x30 ata_tdev_delete+0x24/0x50 [libata]
ata_tlink_delete+0x40/0xa0 [libata]
ata_tport_delete+0x2c/0x60 [libata]
ata_port_detach+0x148/0x1b0 [libata]
ata_pci_remove_one+0x50/0x80 [libata]
ahci_remove_one+0x4c/0x8c [ahci]
Fix this by checking and handling return value of transport_add_device() in ata_tdev_add(). In the error path, device_del() is called to delete the device which was added earlier in this function, and ata_tdev_free() is called to free ata_dev.
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Analysis
by VulDB Data Team • 11/10/2025
The vulnerability described in CVE-2022-49823 represents a critical null pointer dereference issue within the Linux kernel's libata subsystem, specifically affecting the ata_tdev_add() function. This flaw occurs during the dynamic removal of kernel modules and stems from inadequate error handling in the device transport layer. The issue manifests when the transport_add_device() function returns an error condition that is not properly checked, leading to subsequent operations attempting to reference a null pointer. According to the kernel's memory management and device model architecture, this vulnerability directly violates the principle of proper resource initialization and error propagation that should be maintained throughout kernel subsystems. The flaw demonstrates a classic pattern of error handling failure where the absence of validation for function return codes creates a dangerous state that can result in system crashes or potential privilege escalation vectors.
The technical implementation of this vulnerability involves the ATA transport layer within the libata subsystem, which manages communication with ATA devices including hard drives and solid-state drives. When the ata_tdev_add() function attempts to register a device through transport_add_device(), it fails to validate whether the operation succeeded. This oversight creates a scenario where subsequent cleanup operations such as transport_remove_device() are invoked on a device that was never properly added to the system's device hierarchy. The kernel's device model relies on proper reference counting and device registration to maintain system stability, and this failure breaks that fundamental assumption. The call trace reveals a cascading failure path starting from device_del() which ultimately leads to a null pointer dereference at virtual address 0x00000000000000d0, indicating that the kernel attempted to access memory that was never properly allocated or registered.
The operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the integrity of storage subsystems and overall system stability. When triggered during module removal operations, this vulnerability can cause kernel oops or system panics that may result in data loss or forced system reboots. The vulnerability is particularly concerning in production environments where storage devices are frequently accessed or where automated systems might trigger module loading/unloading operations. The flaw affects the AHCI (Advanced Host Controller Interface) driver and related ATA transport mechanisms, making it relevant to a wide range of storage hardware configurations. According to the ATT&CK framework, this vulnerability could be leveraged as part of a broader attack chain to achieve privilege escalation or system compromise, particularly in scenarios where an attacker can control module loading/unloading sequences. The CWE classification for this issue would be CWE-476: NULL Pointer Dereference, which is a well-documented weakness in software development practices.
Mitigation strategies for CVE-2022-49823 require immediate patch application to the Linux kernel, specifically addressing the missing return value check in the ata_tdev_add() function. The fix implements proper error handling by checking the return value of transport_add_device() and ensuring that cleanup operations are only performed on successfully registered devices. This approach aligns with the principle of defensive programming and proper resource management that is fundamental to kernel security. System administrators should prioritize applying the patched kernel version as soon as possible, particularly in environments where storage subsystem stability is critical. The fix also incorporates proper error path handling that ensures device_del() is only called on devices that were successfully added, and that ata_tdev_free() is invoked to clean up allocated resources in error scenarios. Organizations should implement monitoring systems to detect potential exploitation attempts through abnormal module loading/unloading patterns, as this vulnerability could be abused to trigger denial-of-service conditions or potentially facilitate more advanced attack vectors.