CVE-2026-53325
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile — higher than 2% of all known CVEs
Summary
In the Linux kernel AMD64 AGP driver, a vulnerability was found due to incorrect error checking of the return value from cache_nbs(). When no physical AMD northbridge is present (e.g., in virtualized environments), the function returns -ENODEV, but the code only checks for -1, masking the error and leading to a NULL pointer dereference in amd64_fetch_size().
Risk Assessment
The risk involves a potential General Protection Fault (GPF) and system hang in virtualized environments or hardware without an AMD northbridge, which could disrupt services.
Recommendation
Immediately update the Linux kernel to a version containing the fix that changes the error check condition from '== -1' to '< 0' in the agp_amd64_probe() function.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: agp/amd64: Fix broken error propagation in agp_amd64_probe() A NULL pointer dereference was observed in the AMD64 AGP driver when running in a virtualized environment (e.g. qemu/kvm) without a physical AMD northbridge. The crash occurs in amd64_fetch_size() when attempting to dereference the pointer returned by node_to_amd_nb(0). The root cause of this crash is broken error propagation in agp_amd64_probe(): When no AMD northbridges are found, cache_nbs() correctly returns -ENODEV. However, the probe function erroneously checks the return value against exactly -1, rather than < 0. As a result, the hardware absence error is masked, allowing the driver to improperly proceed with initialization. It eventually calls agp_add_bridge(), which invokes amd64_fetch_size(). Since the hardware does not exist, node_to_amd_nb(0) returns NULL, leading to a General Protection Fault (GPF) when accessing its ->misc member. Fix the issue by correcting the error check in agp_amd64_probe() to abort properly when cache_nbs() returns any negative error code. This prevents the driver from erroneously proceeding without hardware, thereby avoiding the subsequent NULL pointer dereference at its source.