CVE-2023-53847

What it actually does

Failure to validate USB transfer success in alauda_check_media() before consuming received data leads to use of uninitialized kernel memory; additionally performs DMA operations directly against a stack buffer instead of the driver-provided DMA-safe buffer.

Why it matters to the business

Systems using affected Linux kernels with certain USB storage devices may experience kernel instability, crashes, or potential information disclosure, increasing operational risk and maintenance overhead for embedded, server, and desktop deployments.

How an attack unfolds

An attacker supplies a malicious or faulty USB device that causes the alauda subdriver to issue a USB transfer which fails; the code then proceeds to interpret the uninitialized buffer contents, potentially triggering memory-safety violations that an attacker could attempt to influence for local privilege escalation or denial of service.

How to fix it

Update the Linux kernel to the commit 153c3e85873cc3e2f387169783c3a227bad9a95a or later stable releases that contain the fix; rebuild and deploy the updated kernel across all affected systems.

How to confirm the fix worked

Confirm the running kernel contains commit 153c3e85873cc3e2f387169783c3a227bad9a95a via git log or kernel version string; recompile with KMSAN and re-test with the original syzkaller reproducer to verify absence of the uninit-value report.

Typical attack path

1. Connect a specially crafted USB storage device recognized by the alauda driver
2. Trigger media status or transport operations that invoke alauda_check_media()
3. Cause the underlying USB control or bulk transfer to fail or return partial data
4. Kernel proceeds to read uninitialized memory from the stack buffer
5. Resulting memory-safety fault is processed by the kernel, potentially allowing attacker-controlled behavior

How to detect it

Search kernel logs and dmesg for KMSAN uninit-value reports referencing alauda_check_media, alauda_transport, or alauda_get_media_status; inspect USB device insertion events correlated with usb-storage driver activity.

• BUG: KMSAN: uninit-value in alauda_transport
• alauda_check_media+0x344
• drivers/usb/storage/alauda.c:460
• alauda_check_media+0x344/0x3310

What your security team should do

• Apply the referenced kernel commit immediately on all systems exposing USB storage functionality
• Restrict untrusted USB devices via USBGuard or kernel module blacklisting until patched
• Monitor kernel logs for KMSAN and usb-storage warnings during the remediation window