CVE-2022-49258 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
crypto: ccree - Fix use after free in cc_cipher_exit()
kfree_sensitive(ctx_p->user.key) will free the ctx_p->user.key. But ctx_p->user.key is still used in the next line, which will lead to a use after free.
We can call kfree_sensitive() after dev_dbg() to avoid the uaf.
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Analysis
by VulDB Data Team • 02/26/2025
The vulnerability CVE-2022-49258 represents a critical use after free condition within the Linux kernel's cryptographic subsystem, specifically affecting the ccree driver responsible for hardware acceleration of cryptographic operations. This flaw resides in the crypto framework's handling of cipher contexts and demonstrates a classic memory safety issue that could potentially be exploited by malicious actors to compromise system integrity. The vulnerability occurs during the cleanup phase of cryptographic cipher operations when the kernel attempts to free memory resources while simultaneously referencing them in subsequent operations.
The technical implementation flaw stems from improper memory management within the cc_cipher_exit() function where the kernel scheduler executes kfree_sensitive(ctx_p->user.key) to release memory allocated for cryptographic keys. However, the code structure places this memory deallocation operation before the final usage of ctx_p->user.key in a subsequent dev_dbg() debugging call, creating a scenario where freed memory is accessed after deallocation. This pattern violates fundamental memory safety principles and creates a predictable access violation that could be leveraged for arbitrary code execution or system instability.
The operational impact of this vulnerability extends beyond simple memory corruption as it affects the core cryptographic infrastructure of Linux systems, potentially compromising the security of encrypted communications, file systems, and authentication mechanisms that rely on the ccree driver for hardware-accelerated cryptographic processing. Attackers could exploit this condition to gain elevated privileges or cause denial of service conditions, particularly in environments where hardware cryptographic accelerators are actively utilized for security-critical operations.
Security professionals should note that this vulnerability aligns with CWE-416, which specifically addresses use after free conditions in software implementations. The fix implemented in the kernel patch demonstrates proper memory management practices by reordering the execution sequence to perform the kfree_sensitive() operation after the debugging output, thereby eliminating the race condition that enabled the use after free scenario. Organizations should prioritize applying this kernel update as it represents a direct mitigation against potential exploitation attempts targeting cryptographic subsystems.
The remediation approach taken by kernel developers follows established security best practices for memory management in kernel space operations, emphasizing the importance of maintaining proper resource lifecycle management throughout cryptographic operations. This fix exemplifies the critical nature of defensive programming in kernel code where debugging operations must not interfere with memory deallocation sequences. System administrators should ensure that all Linux systems utilizing cryptographic hardware accelerators receive this patch promptly to maintain the integrity of their security infrastructure and prevent potential exploitation through memory corruption attacks.