CVE-2024-40937 in Linux
Summary
by MITRE • 07/12/2024
In the Linux kernel, the following vulnerability has been resolved:
gve: Clear napi->skb before dev_kfree_skb_any()
gve_rx_free_skb incorrectly leaves napi->skb referencing an skb after it is freed with dev_kfree_skb_any(). This can result in a subsequent call to napi_get_frags returning a dangling pointer.
Fix this by clearing napi->skb before the skb is freed.
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Analysis
by VulDB Data Team • 10/07/2025
The vulnerability identified as CVE-2024-40937 resides within the Linux kernel's gve network driver implementation, specifically addressing a critical memory management issue that could lead to system instability and potential security implications. This flaw affects the gve_rx_free_skb function which handles the cleanup of received network packets within the generic virtio ethernet driver. The vulnerability manifests when the driver fails to properly manage the napi->skb pointer during packet deallocation, creating a scenario where stale references persist in memory even after the underlying skb structure has been freed.
The technical root cause of this vulnerability stems from improper pointer management within the network packet processing pipeline. When the gve_rx_free_skb function processes a received packet, it calls dev_kfree_skb_any() to release the skb memory back to the system. However, the function does not clear the napi->skb pointer before this deallocation occurs, leaving a dangling reference that points to memory that has already been freed. This memory management error creates a scenario where subsequent operations attempting to access napi->skb may encounter corrupted or invalid memory locations, potentially leading to unpredictable behavior.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can affect the stability and reliability of network operations within the Linux kernel. When napi_get_frags is subsequently called, it may return a dangling pointer that references deallocated memory, potentially causing kernel panics, system crashes, or data corruption. This type of vulnerability represents a classic use-after-free condition that can be exploited by malicious actors to gain unauthorized access to system resources or disrupt normal network operations. The issue particularly affects systems utilizing the gve network driver, which is commonly found in virtualized environments and cloud computing platforms where virtio network interfaces are prevalent.
This vulnerability aligns with CWE-416, which describes the use of freed memory condition, and can be categorized under ATT&CK technique T1059.001 for command and scripting interpreter execution, as exploitation could potentially lead to privilege escalation or denial of service attacks. The fix implemented addresses this by ensuring that napi->skb is cleared before dev_kfree_skb_any() is called, effectively preventing the dangling pointer scenario. This remediation follows established best practices for memory management in kernel space, where proper pointer invalidation prevents use-after-free vulnerabilities. The solution demonstrates a fundamental principle of secure coding that emphasizes the importance of maintaining consistent state management throughout memory lifecycle operations, particularly in critical kernel components that handle network packet processing and memory allocation.
The resolution of CVE-2024-40937 represents a crucial maintenance update for Linux kernel distributions that utilize the gve network driver, particularly in virtualized environments where network performance and stability are paramount. System administrators should prioritize applying this patch to mitigate potential security risks and ensure continued system reliability. The fix exemplifies the importance of rigorous code review processes in kernel development, where even seemingly minor memory management issues can have significant operational consequences. This vulnerability serves as a reminder of the critical importance of proper resource management in kernel space, where memory corruption issues can directly impact system security and availability. The patch implementation ensures that network drivers maintain proper state consistency during packet processing, preventing potential exploitation scenarios that could compromise system integrity.