CVE-2023-50431 Overview
CVE-2023-50431 is an information disclosure vulnerability in the Linux kernel through version 6.6.5. The flaw resides in the sec_attest_info function within drivers/accel/habanalabs/common/habanalabs_ioctl.c, part of the HabanaLabs accelerator driver. The info->pad0 structure field is not initialized before being copied to user space, allowing a local authenticated user to read uninitialized kernel memory contents.
Critical Impact
A local user with access to the HabanaLabs ioctl interface can leak uninitialized kernel stack or heap memory, potentially exposing sensitive data useful for further attacks against the kernel.
Affected Products
- Linux Kernel versions through 6.6.5
- Systems using the HabanaLabs accelerator driver (drivers/accel/habanalabs)
- Distributions shipping affected kernel releases without the upstream fix
Discovery Timeline
- 2023-12-09 - CVE-2023-50431 published to the National Vulnerability Database
- 2025-05-30 - Last updated in NVD database
Technical Details for CVE-2023-50431
Vulnerability Analysis
The vulnerability is an uninitialized memory disclosure in the HabanaLabs accelerator driver, classified under [NVD-CWE-noinfo]. The sec_attest_info handler constructs a response structure that is returned to user space through an ioctl call. The structure contains a padding field named pad0 that the kernel code fails to zero-initialize before the copy operation to user space.
When a local process invokes the relevant ioctl, the kernel allocates the response structure on the stack or heap. The contents of pad0 retain whatever bytes were previously stored at that memory location. The driver then copies the full structure, including the uninitialized padding bytes, back to the caller.
An attacker can repeatedly invoke the ioctl to harvest residual kernel memory. Leaked bytes may include pointers useful for bypassing Kernel Address Space Layout Randomization (KASLR), cryptographic material, or fragments of other processes' data residing in the kernel.
Root Cause
The root cause is missing initialization of structure padding before user-space copy. Compilers insert padding bytes between structure members for alignment, and these bytes are not automatically zeroed. The fix, applied in upstream commit a9f07790a4b2250f0140e9a61c7f842fd9b618c7, ensures the structure is fully zeroed prior to population.
Attack Vector
Exploitation requires local access with low privileges and the ability to open the HabanaLabs character device. No user interaction is needed. The attacker issues the sec_attest_info ioctl, reads the returned buffer, and extracts uninitialized bytes. Refer to the upstream commit for the patch details.
// Code example not available - see the upstream kernel commit linked above
// for the exact patch implementing memset-based zero initialization of the
// sec_attest_info response structure prior to copy_to_user().
Detection Methods for CVE-2023-50431
Indicators of Compromise
- Unexpected processes opening /dev/accel/accel* or HabanaLabs device nodes on systems without AI accelerator workloads
- Repeated ioctl invocations against the HabanaLabs driver from non-privileged user contexts
- Unprivileged local accounts performing kernel memory reconnaissance activity
Detection Strategies
- Audit kernel version using uname -r and compare against patched releases to identify exposed hosts
- Enable auditd rules for openat and ioctl syscalls targeting HabanaLabs device files
- Correlate ioctl activity with process lineage to flag non-accelerator workloads accessing the driver
Monitoring Recommendations
- Track installed kernel packages across the fleet and alert on systems running Linux kernel 6.6.5 or earlier with the HabanaLabs driver loaded
- Monitor for module load events for habanalabs on hosts that do not require the accelerator
- Forward syscall audit logs to a central analytics platform for retrospective hunting of ioctl abuse patterns
How to Mitigate CVE-2023-50431
Immediate Actions Required
- Apply the upstream Linux kernel patch from commit a9f07790a4b2250f0140e9a61c7f842fd9b618c7 or upgrade to a kernel release that includes the fix
- Restrict access to HabanaLabs device nodes to trusted service accounts only
- Inventory systems running kernel 6.6.5 or earlier with the habanalabs driver and prioritize patching
Patch Information
The fix is committed upstream in the Linux kernel tree at Linux Kernel Commit a9f07790. Distribution maintainers have backported the change to stable branches. Discussion of the fix appears on the Freedesktop.org DRI Development list. Administrators should rebuild custom kernels or install vendor-provided updates that incorporate this commit.
Workarounds
- Unload the habanalabs kernel module on hosts that do not require AI accelerator functionality using modprobe -r habanalabs
- Blacklist the driver by adding blacklist habanalabs to /etc/modprobe.d/ configuration
- Tighten permissions on HabanaLabs device nodes so only authorized service users can issue ioctls
# Verify kernel version and module status
uname -r
lsmod | grep habanalabs
# Temporarily unload the driver if not in use
sudo modprobe -r habanalabs
# Persistently blacklist the module
echo 'blacklist habanalabs' | sudo tee /etc/modprobe.d/blacklist-habanalabs.conf
sudo update-initramfs -u
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
