CVE-2022-48629 is a vulnerability in the Linux kernel's Qualcomm random number generator (qcom-rng) driver. The issue arises because the qcom_rng_read() function does not properly verify that the buffer it fills with random data is completely populated before returning success. Specifically, the generate function in the rng_alg structure expects the destination buffer to be fully filled if it returns 0 (success). However, qcom_rng_generate() can partially fill the buffer with random data and leave the remainder zeroed if a certain status check ('val & PRNG_STATUS_DATA_AVAIL') fails. This results in large sections of the output buffer containing zeros rather than random data, degrading the quality of randomness. This was demonstrated by running the kcapi-rng tool to generate a large random data file, which showed significant zeroed sections and poor entropy statistics before the patch. After the patch, the qcom_rng_generate() function was corrected to return the proper status, and qcom_rng_read() was fixed to ensure the buffer is fully filled before returning success. This leads to significantly improved randomness quality, as confirmed by entropy tests (ent project) showing near-ideal entropy and statistical randomness metrics. The vulnerability affects Linux kernel versions containing the Qualcomm RNG driver code prior to the patch and was tested on devices such as the Nexus 5 (msm8974 SoC). While no known exploits are reported in the wild, the vulnerability could impact any cryptographic operations relying on this RNG source, potentially weakening cryptographic keys or operations that depend on high-quality randomness.

For European organizations, this vulnerability could have serious implications if they use affected Linux kernel versions on Qualcomm-based hardware platforms, especially embedded systems, mobile devices, or specialized network equipment. The compromised randomness quality could lead to weakened cryptographic keys, predictable session tokens, or other security-critical random values, undermining confidentiality and integrity of communications and stored data. This is particularly critical for sectors relying heavily on cryptography such as finance, healthcare, telecommunications, and government agencies. The impact is more pronounced in environments where the Qualcomm RNG is a primary or significant entropy source. While the vulnerability does not directly cause system crashes or denial of service, the cryptographic weakening could facilitate further attacks such as key recovery or session hijacking. Given the widespread use of Linux in servers and embedded devices across Europe, and the presence of Qualcomm chipsets in many mobile and IoT devices, the threat surface is notable. However, the vulnerability requires the affected RNG driver to be in use, so systems not using Qualcomm RNG or running updated kernels are not impacted.

European organizations should prioritize updating Linux kernels to versions that include the patch for CVE-2022-48629. Specifically, ensure that all devices using Qualcomm RNG drivers are running patched kernel versions where qcom_rng_generate() and qcom_rng_read() functions have been corrected. For embedded and mobile devices, coordinate with hardware vendors and OEMs to obtain firmware or OS updates that incorporate the fix. Additionally, organizations should audit their cryptographic modules and RNG sources to verify that they do not rely solely on the Qualcomm RNG or have fallback entropy sources. Implementing additional entropy gathering mechanisms or using hardware RNGs from trusted vendors can mitigate risks. For critical systems, consider performing entropy quality tests on random data outputs to detect anomalies. Monitoring for kernel updates and subscribing to Linux security advisories is essential. Finally, in environments where patching is delayed, cryptographic keys generated during the vulnerable period should be considered potentially compromised and rotated accordingly.