Bug 2425051 (CVE-2023-54065)

Summary: CVE-2023-54065 kernel: Linux kernel: Privilege escalation in Realtek MDIO driver due to out-of-bounds write
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's `realtek-mdio` driver. The `probe` function incorrectly allocates memory, leading to an out-of-bounds write. A local attacker could exploit this memory corruption to cause a denial of service or potentially escalate privileges on the system.
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Description OSIDB Bzimport 2025-12-24 13:04:49 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: realtek: fix out-of-bounds access

The probe function sets priv->chip_data to (void *)priv + sizeof(*priv)
with the expectation that priv has enough trailing space.

However, only realtek-smi actually allocated this chip_data space.
Do likewise in realtek-mdio to fix out-of-bounds accesses.

These accesses likely went unnoticed so far, because of an (unused)
buf[4096] member in struct realtek_priv, which caused kmalloc to
round up the allocated buffer to a big enough size, so nothing of
value was overwritten. With a different allocator (like in the barebox
bootloader port of the driver) or with KASAN, the memory corruption
becomes quickly apparent.
Comment 1 Alexander B 2025-12-25 06:11:09 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122429-CVE-2023-54065-1de4@gregkh/T