Medium [CVE-2026-53325] Fix broken error propagation in agp_amd64_probe
This medium-severity Red Hat Linux advisory covers CVE-2026-53325 affecting Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat package: kernel-rt.
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Summary
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 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. This vulnerability occurs in virtualized environments lacking a physical AMD northbridge.
Due to incorrect error handling, the driver attempts to initialize without the required hardware, leading to a NULL pointer dereference and causing the system to crash. This can result in a Denial of Service (DoS) for the affected system.
Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-476.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 8 days ago·verify at source
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