CVE-2026-80522 in Linux
Summary
by MITRE • 08/26/2026
In the Linux kernel, the following vulnerability has been resolved:
crypto: tegra - fix rctx->cryptlen calculation in tegra_gcm_do_one_req()
Perform rctx->cryptlen calculation in tegra_gcm_do_one_req() the same way it is done in tegra_ccm_crypt_init(). The current formulae may lead to a crash if a caller does not call tegra_gcm_setauthsize() and so ctx->authsize remains zero. Then a decrypt operation with incorrect rctx->cryptlen will lead to a write beyound rctx->dst_sg buffer.
As a follow-up cleanup delete struct tegra_aead_ctx->authsize field since it appears to be completely unused. Also simplify tegra_ccm_setauthsize() and tegra_gcm_setauthsize() functions respectively.
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Analysis
by VulDB Data Team • 08/26/2026
The Linux kernel's cryptographic subsystem for NVIDIA Tegra hardware contains a critical implementation flaw within the GCM mode encryption driver, specifically in the function tegra_gcm_do_one_req(). This vulnerability stems from an incorrect calculation of the cryptlen variable, which determines the length of data to be processed during cryptographic operations. The root cause lies in a discrepancy between how rctx->cryptlen is computed in this specific request handler versus its correct implementation in the related CCM mode initialization function tegra_ccm_crypt_init(). When developers maintain inconsistent logic for calculating buffer lengths across similar cryptographic modes, it introduces subtle but severe memory safety violations that can be exploited under specific conditions.
The operational impact of this flaw becomes apparent when a user-space application or kernel module performs decryption operations without explicitly setting the authentication size via tegra_gcm_setauthsize(). In such scenarios, the context variable ctx->authsize remains at its default value of zero. The flawed calculation logic then produces an incorrect rctx->cryptlen value that does not accurately reflect the actual data boundaries required for safe processing. This miscalculation directly leads to a buffer overflow condition where the driver attempts to write beyond the allocated destination scatter-gather list, known as rctx->dst_sg. Such out-of-bounds writes constitute a severe memory corruption vulnerability that can compromise system stability and potentially allow arbitrary code execution if an attacker can control the data being decrypted and trigger this specific code path.
From a classification perspective, this vulnerability aligns with CWE-787: Out-of-bounds Write, as it involves writing to a memory location outside the intended buffer boundaries due to improper length calculation. It also relates to CWE-20: Improper Input Validation, since the driver fails to adequately validate or initialize parameters that dictate memory access limits before performing cryptographic operations. In terms of attack vectors and techniques, this flaw could be leveraged in an exploitation scenario similar to ATT&CK technique T1564.003: Hidden Window, where malicious actors might attempt to hide their activities by exploiting kernel-level memory corruption to escalate privileges or bypass security controls. The lack of proper bounds checking allows for potential privilege escalation from user space to kernel space if the overflow overwrites critical kernel structures such as function pointers or return addresses on the stack.
The resolution implemented in this update corrects the cryptlen calculation logic within tegra_gcm_do_one_req() to match the established pattern used in tegra_ccm_crypt_init(), thereby ensuring that memory access remains strictly within allocated boundaries regardless of whether authsize is explicitly set by the caller. Additionally, as part of a broader code hygiene effort, developers removed the unused struct member ctx->authsize from tegra_aead_ctx and simplified the corresponding setauthsize functions for both CCM and GCM modes. These changes not only fix the immediate security risk but also reduce technical debt and potential future confusion regarding parameter initialization requirements.
To mitigate this vulnerability in environments running affected kernel versions, administrators should apply the latest available kernel patches that include these specific fixes. For systems where immediate patching is not feasible, implementing strict input validation at higher layers of the application stack can help ensure that authsize parameters are always explicitly defined before invoking cryptographic operations through the Tegra hardware interface. Furthermore, enabling Kernel Self-Protection Project (KSPCC) features such as Stack Protector and KASLR provides additional layers of defense against exploitation attempts resulting from memory corruption vulnerabilities like this one. Regular security audits focusing on crypto driver implementations can help identify similar inconsistencies in length calculations across other subsystems before they are exploited in production environments.