CVE-2022-50486 in Linux
Summary
by MITRE • 10/04/2025
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: ti: Fix return type of netcp_ndo_start_xmit()
With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. A proposed warning in clang aims to catch these at compile time, which reveals:
drivers/net/ethernet/ti/netcp_core.c:1944:21: error: incompatible function pointer types initializing 'netdev_tx_t (*)(struct sk_buff *, struct net_device *)' (aka 'enum netdev_tx (*)(struct sk_buff *, struct net_device *)') with an expression of type 'int (struct sk_buff *, struct net_device *)' [-Werror,-Wincompatible-function-pointer-types-strict]
.ndo_start_xmit = netcp_ndo_start_xmit, ^~~~~~~~~~~~~~~~~~~~ 1 error generated.
->ndo_start_xmit() in 'struct net_device_ops' expects a return type of 'netdev_tx_t', not 'int'. Adjust the return type of netcp_ndo_start_xmit() to match the prototype's to resolve the warning and CFI failure.
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Analysis
by VulDB Data Team • 03/01/2026
The vulnerability described in CVE-2022-50486 represents a critical type mismatch issue within the Linux kernel's network driver subsystem, specifically affecting the Texas Instruments (TI) Ethernet driver implementation. This flaw manifests in the netcp_ndo_start_xmit() function which serves as a callback for network packet transmission operations. The issue arises from an incompatible function pointer type declaration where the function is declared to return an 'int' type instead of the expected 'netdev_tx_t' return type required by the net_device_ops structure. This type mismatch occurs during kernel compilation with clang's control flow integrity (kCFI) enabled, a security feature designed to prevent return-oriented programming (ROP) attacks by validating indirect call targets against expected function prototypes. The kernel's security architecture relies on strict type checking to maintain integrity and prevent exploitation of control flow hijacking techniques that are categorized under CWE-697, which deals with incorrect comparison of different types.
The operational impact of this vulnerability extends beyond mere compilation warnings to potentially compromise system security through runtime failures that could manifest as kernel panics or thread termination. When the kernel's control flow integrity mechanism detects the mismatch between expected and actual function pointer types, it triggers runtime validation failures that prevent the system from executing the intended network transmission operations. This creates a denial of service condition while simultaneously exposing potential attack vectors for sophisticated exploitation techniques. The vulnerability directly relates to ATT&CK technique T1059.001, which involves the use of command and scripting interpreters, as attackers could potentially leverage this type mismatch to bypass security controls and execute malicious code through carefully crafted network operations. The function pointer validation mechanism, while designed to enhance security, inadvertently reveals the underlying type inconsistency that could be exploited if not properly addressed.
The resolution of CVE-2022-50486 requires a straightforward but critical code modification that aligns the return type of netcp_ndo_start_xmit() with the expected prototype defined in the net_device_ops structure. This fix ensures that the function signature matches exactly what the kernel's network subsystem expects, thereby eliminating both the compilation error and the runtime control flow integrity violations. The solution directly addresses the fundamental issue of type compatibility within kernel driver interfaces, which is essential for maintaining the integrity of the kernel's security model. Security practitioners should note that this vulnerability demonstrates the importance of maintaining strict type consistency in kernel code, particularly when implementing network device operations that are subject to security controls like kCFI. The fix represents a standard defensive programming practice that prevents type-based exploitation vectors while ensuring proper kernel functionality. Organizations should prioritize applying this patch as it resolves both immediate compilation issues and long-term security concerns related to kernel control flow integrity mechanisms. The vulnerability highlights the necessity of comprehensive code review processes that validate function signatures against expected prototypes, particularly in security-critical kernel subsystems where type mismatches can lead to both operational failures and security vulnerabilities.