CVE-2022-48854 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
net: arc_emac: Fix use after free in arc_mdio_probe()
If bus->state is equal to MDIOBUS_ALLOCATED, mdiobus_free(bus) will free the "bus". But bus->name is still used in the next line, which will lead to a use after free.
We can fix it by putting the name in a local variable and make the bus->name point to the rodata section "name",then use the name in the error message without referring to bus to avoid the uaf.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 07/23/2024
The vulnerability CVE-2022-48854 represents a critical use-after-free condition in the Linux kernel's ARC EMAC network driver implementation. This flaw exists within the arc_mdio_probe() function where improper memory management leads to potential system instability and security risks. The issue specifically manifests when the MDIO bus state equals MDIOBUS_ALLOCATED, creating a scenario where memory deallocation occurs before subsequent access to the freed memory structure.
The technical root cause involves a race condition between memory deallocation and subsequent memory access patterns. When mdiobus_free(bus) is called, the bus structure itself gets freed from memory, yet the code continues to reference bus->name in the following line of execution. This creates a classic use-after-free scenario where the program attempts to access memory that has already been released, potentially leading to undefined behavior, system crashes, or exploitation by malicious actors. The vulnerability falls under CWE-416, which specifically addresses use-after-free conditions in memory management.
From an operational perspective, this vulnerability poses significant risks to embedded systems and network infrastructure that rely on the ARC EMAC driver. The flaw could lead to network connectivity failures, system panics, or more critically, provide an attack vector for privilege escalation or denial-of-service attacks. Network devices using the affected kernel versions may experience unexpected behavior when initializing MDIO buses, particularly during device probe operations. The impact extends beyond simple functionality degradation to potentially compromising the entire system stability.
The mitigation strategy involves implementing proper memory management practices by storing the bus name in a local variable before calling mdiobus_free(). This approach ensures that the string reference remains valid even after the bus structure is freed. The fix aligns with ATT&CK technique T1068 by preventing privilege escalation through memory corruption vulnerabilities, while also addressing defensive measures against use-after-free exploitation patterns. System administrators should prioritize applying kernel updates containing this fix, particularly in environments where network reliability and system stability are critical requirements. The solution demonstrates proper defensive programming practices by ensuring memory access patterns do not reference freed structures, thereby preventing the exploitation of memory corruption vulnerabilities that could otherwise be leveraged for unauthorized system access.