CVE-2022-48750 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (nct6775) Fix crash in clear_caseopen
Paweł Marciniak reports the following crash, observed when clearing the chassis intrusion alarm.
BUG: kernel NULL pointer dereference, address: 0000000000000028 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 3 PID: 4815 Comm: bash Tainted: G S 5.16.2-200.fc35.x86_64 #1 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./Z97 Extreme4, BIOS P2.60A 05/03/2018 RIP: 0010:clear_caseopen+0x5a/0x120 [nct6775]
Code: 68 70 e8 e9 32 b1 e3 85 c0 0f 85 d2 00 00 00 48 83 7c 24 ... RSP: 0018:ffffabcb02803dd8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000 RDX: ffff8e8808192880 RSI: 0000000000000000 RDI: ffff8e87c7509a68 RBP: 0000000000000000 R08: 0000000000000001 R09: 000000000000000a R10: 000000000000000a R11: f000000000000000 R12: 000000000000001f R13: ffff8e87c7509828 R14: ffff8e87c7509a68 R15: ffff8e88494527a0 FS: 00007f4db9151740(0000) GS:ffff8e8ebfec0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000028 CR3: 0000000166b66001 CR4: 00000000001706e0 Call Trace: kernfs_fop_write_iter+0x11c/0x1b0 new_sync_write+0x10b/0x180 vfs_write+0x209/0x2a0 ksys_write+0x4f/0xc0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae
The problem is that the device passed to clear_caseopen() is the hwmon device, not the platform device, and the platform data is not set in the hwmon device. Store the pointer to sio_data in struct nct6775_data and get if from there if needed.
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Analysis
by VulDB Data Team • 08/17/2025
The vulnerability CVE-2022-48750 represents a critical null pointer dereference issue within the Linux kernel's hardware monitoring subsystem, specifically affecting the nct6775 driver used for chip monitoring. This flaw manifests when attempting to clear chassis intrusion alarms through the hwmon interface, creating a potential system crash scenario that could be exploited to disrupt system operations or potentially escalate privileges. The issue stems from an improper handling of device context pointers within the driver's implementation, where the function clear_caseopen receives a hwmon device pointer instead of the expected platform device pointer, leading to a direct dereference of an uninitialized or invalid memory location at address 0x28.
The technical root cause of this vulnerability lies in the improper data structure management within the nct6775 driver implementation. When the clear_caseopen function executes, it attempts to access platform-specific data stored in the sio_data structure, but the function receives a hwmon device context rather than the platform device context where this data is properly initialized. This mismatch creates a NULL pointer dereference condition that triggers a kernel oops and system crash. The vulnerability aligns with CWE-476, which describes null pointer dereference conditions in software systems, and demonstrates poor error handling practices in kernel space device drivers. The call trace shows the execution path leading to the crash through kernfs_fop_write_iter, indicating that the issue occurs during file system write operations targeting hardware monitoring interfaces.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential denial-of-service condition that could be triggered by unprivileged users or processes attempting to interact with the hardware monitoring subsystem. Attackers could exploit this weakness to repeatedly trigger the crash condition, causing system instability and potentially disrupting critical server operations or embedded systems that rely on hardware monitoring capabilities. The vulnerability affects systems running kernel versions including 5.16.2 and is particularly concerning in enterprise environments where hardware monitoring is essential for system health assessment and proactive maintenance. From an ATT&CK perspective, this vulnerability could be leveraged in the context of privilege escalation or denial-of-service attacks, potentially serving as an initial foothold for more sophisticated exploitation attempts.
Mitigation strategies for CVE-2022-48750 involve applying the official kernel patch that resolves the pointer management issue by properly storing the sio_data pointer within the nct6775_data structure and retrieving it appropriately when needed. System administrators should ensure immediate patch deployment across all affected systems, particularly those running kernel versions 5.16.2 and earlier. Additionally, implementing proper input validation and error handling within hardware monitoring interfaces can help prevent similar issues in other kernel subsystems. Monitoring for unusual patterns in hardware monitoring interface access and implementing proper system hardening measures can provide additional defense-in-depth against exploitation attempts. The fix addresses the core issue by ensuring proper context management between hwmon and platform device interfaces, thereby preventing the null pointer dereference condition that previously led to system crashes and maintaining the stability of hardware monitoring functionality across affected systems.