CVE-2023-54325

Vulnerability

Description

In the Linux kernel's QAT (QuickAssist Technology) crypto driver, an out-of-bounds read vulnerability exists in the qat_alg_skcipher_init_com function when preparing an AER-CTR request. The driver copies a user-provided key into a firmware-accessible data structure. For QAT GEN4 devices, the key size is rounded up by 16 bytes because the device expects a rounded-up size. However, the rounding occurs before the copy is performed before the key is copied, causing the copy operation to read beyond the bounds of the key buffer. This results in a global out-of-bounds read, as reported by KASAN [1].

Exploitation

An attacker can trigger this vulnerability by supplying a key of a size that, when rounded up, exceeds the actual key buffer size. The attack requires the ability to set a cryptographic key via the kernel's crypto API, typically through a crypto_skcipher_setkey call. No special privileges are needed beyond access to the crypto subsystem, which is available to unprivileged users in many configurations. The vulnerability is exploitable when the target device is a QAT GEN4 accelerator [1].

Impact

A successful out-of-bounds read can leak sensitive kernel memory contents to the attacker. The KASAN report shows a read of 32 bytes from a global variable, which could include cryptographic keys, passwords, or other confidential data. This information disclosure could be used to further compromise the system's security, potentially leading to further attacks [1].

Mitigation

The fix is to perform the key copy first and then update the key length, ensuring that the copy size does not exceed the actual key buffer. The patch has been applied to the Linux kernel stable branches, as seen in the referenced commits [1][2][3][4]. Users should update their kernel versions containing this vulnerability should update to a patched version. No workaround is available other than applying the kernel patch.