CVE-2022-49448 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
soc: bcm: Check for NULL return of devm_kzalloc()
As the potential failure of allocation, devm_kzalloc() may return NULL. Then the 'pd->pmb' and the follow lines of code may bring null pointer dereference.
Therefore, it is better to check the return value of devm_kzalloc() to avoid this confusion.
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Analysis
by VulDB Data Team • 03/05/2025
This vulnerability exists within the Linux kernel's Broadcom system-on-chip (soc) driver implementation where a critical null pointer dereference risk emerges from improper error handling during memory allocation operations. The issue specifically affects the device memory management subsystem where devm_kzalloc() function is utilized to allocate memory for power management block structures. When this allocation function fails and returns NULL, subsequent code execution attempts to dereference the null pointer through pd->pmb access, creating a potential crash condition that could be exploited to disrupt system operations or potentially escalate privileges.
The technical flaw stems from the absence of proper return value validation after calling devm_kzalloc() within the Broadcom soc driver codebase. This memory allocation function is designed to automatically manage memory cleanup during device removal, but it can legitimately return NULL when system memory is exhausted or allocation fails. The vulnerability represents a classic null pointer dereference issue that maps directly to CWE-476, which identifies NULL pointer dereference as a fundamental programming error that can lead to system instability and potential security implications. Without proper error checking, the kernel continues execution assuming successful allocation, leading to immediate system crash when attempting to access memory locations pointed to by the null reference.
The operational impact of this vulnerability extends beyond simple system instability, as it could potentially be exploited by malicious actors to cause denial of service conditions or create opportunities for privilege escalation attacks. When the kernel encounters this null pointer dereference, it typically results in a kernel oops or system crash, which can be particularly problematic in embedded systems or devices where system availability is critical. In enterprise environments, such vulnerabilities could be leveraged to disrupt services or create persistent denial of service conditions that would require system reboot to resolve. The vulnerability affects systems running Linux kernel versions that include the affected Broadcom soc driver code, particularly those implementing power management features that utilize the problematic memory allocation path.
Mitigation strategies for this vulnerability should focus on implementing proper error handling practices within the kernel codebase, specifically ensuring that all return values from devm_kzalloc() are validated before subsequent pointer operations. The recommended approach involves adding explicit NULL checks immediately after memory allocation calls, allowing the driver to gracefully handle allocation failures or propagate appropriate error codes to the calling subsystem. Security teams should prioritize patching affected kernel versions, with the fix requiring modifications to the Broadcom soc driver to validate allocation results before proceeding with pointer dereference operations. This aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a fundamental defensive programming practice that should be applied across all kernel subsystems handling dynamic memory allocation. Organizations should also implement monitoring for kernel oops messages and system crash reports that may indicate exploitation attempts, while maintaining up-to-date kernel versions to prevent similar issues from arising in future deployments.