CVE-2024-47708 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
netkit: Assign missing bpf_net_context
During the introduction of struct bpf_net_context handling for XDP-redirect, the netkit driver has been missed, which also requires it because NETKIT_REDIRECT invokes skb_do_redirect() which is accessing the per-CPU variables. Otherwise we see the following crash:
BUG: kernel NULL pointer dereference, address: 0000000000000038 bpf_redirect() netkit_xmit() dev_hard_start_xmit()
Set the bpf_net_context before invoking netkit_xmit() program within the netkit driver.
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Analysis
by VulDB Data Team • 01/19/2026
The vulnerability CVE-2024-47708 represents a critical kernel-level issue affecting the Linux kernel's networking subsystem, specifically within the netkit driver implementation. This flaw manifests as a NULL pointer dereference during network packet processing, occurring when the kernel attempts to handle XDP (eXpress Data Path) redirects through the netkit driver. The root cause stems from an incomplete implementation of bpf_net_context handling during the introduction of XDP redirect functionality, where the netkit driver was overlooked in the necessary code modifications. This oversight creates a fundamental inconsistency in the kernel's networking infrastructure, as the netkit driver requires proper bpf_net_context initialization to function correctly with NETKIT_REDIRECT operations that invoke skb_do_redirect().
The technical nature of this vulnerability involves a missing initialization step within the netkit driver's packet transmission path. When netkit_xmit() is invoked through XDP redirect operations, the code attempts to access per-CPU variables that depend on the bpf_net_context structure being properly set. Without this initialization, the kernel encounters a NULL pointer dereference at memory address 0x0000000000000038, triggering a kernel oops condition that inevitably leads to system instability and potential denial of service. The crash occurs at the intersection of BPF (Berkeley Packet Filter) networking operations and hardware network interface handling, specifically during the dev_hard_start_xmit() function call sequence. This represents a classic CWE-476 NULL Pointer Dereference vulnerability where the expected context structure fails to be initialized before use, creating a direct pathway for system crashes.
The operational impact of this vulnerability extends beyond simple system crashes to encompass broader network reliability and availability concerns. Systems utilizing netkit drivers for high-performance packet processing become vulnerable to unexpected kernel panics, potentially disrupting network services and causing complete system hangs. Attackers could exploit this vulnerability by triggering XDP redirect operations through crafted network traffic, leading to sustained denial of service conditions that affect network connectivity and system responsiveness. The vulnerability affects systems running Linux kernels where netkit drivers are deployed, particularly those implementing high-speed networking features and BPF-based packet processing. This issue particularly impacts networking infrastructure components, cloud environments, and any systems relying on advanced packet handling capabilities that utilize the netkit driver framework.
Mitigation strategies for CVE-2024-47708 require immediate kernel updates addressing the missing bpf_net_context initialization within the netkit driver. System administrators should prioritize applying the relevant kernel patches that properly initialize bpf_net_context before invoking netkit_xmit() operations. Additionally, monitoring for kernel oops messages and system crashes related to network packet processing can help detect exploitation attempts. The fix involves implementing proper context initialization before the netkit_xmit() function call within the driver's redirect handling code, ensuring that per-CPU variables accessed by skb_do_redirect() are properly populated. Organizations should also consider implementing network traffic monitoring to detect unusual XDP redirect patterns that might indicate exploitation attempts, while maintaining regular kernel update schedules to address similar vulnerabilities in the networking subsystem. This vulnerability aligns with ATT&CK technique T1059.006 for kernel-level exploitation and demonstrates the critical importance of proper context management in kernel space operations.