CVE-2022-48743 in Linux
Summary
by MITRE • 06/20/2024
In the Linux kernel, the following vulnerability has been resolved:
net: amd-xgbe: Fix skb data length underflow
There will be BUG_ON() triggered in include/linux/skbuff.h leading to intermittent kernel panic, when the skb length underflow is detected.
Fix this by dropping the packet if such length underflows are seen because of inconsistencies in the hardware descriptors.
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Analysis
by VulDB Data Team • 10/30/2024
The vulnerability CVE-2022-48743 represents a critical buffer management flaw in the Linux kernel's amd-xgbe network driver implementation that can lead to system instability and potential denial of service conditions. This issue specifically affects the Advanced Micro Devices XGBe (10 Gigabit Ethernet) network driver which is part of the broader networking subsystem of the Linux kernel. The flaw manifests when the driver encounters inconsistent hardware descriptors during packet processing, resulting in a scenario where the socket buffer (skb) data length calculation becomes negative, triggering a kernel panic condition.
The technical root cause of this vulnerability lies in improper validation of hardware descriptor information within the amd-xgbe driver's packet processing pipeline. When hardware descriptors provide inconsistent or malformed length information, the driver fails to properly validate the incoming packet data before attempting to process it. This leads to an integer underflow condition in the socket buffer management code, specifically triggering a BUG_ON() macro defined in include/linux/skbuff.h. The BUG_ON() macro serves as a kernel debugging mechanism that terminates execution when a specified condition evaluates to true, in this case when a negative skb data length is detected. This condition is particularly problematic because it can occur intermittently, making the vulnerability difficult to reproduce and diagnose in production environments.
The operational impact of CVE-2022-48743 extends beyond simple system crashes to potentially compromise network availability and system stability in environments where the affected network driver is actively processing network traffic. When the kernel panic occurs, it results in an immediate system halt that requires manual intervention to recover, effectively creating a denial of service condition for the affected system. The intermittent nature of the vulnerability means that systems may appear stable for extended periods before experiencing a crash, making it particularly dangerous in production environments where network reliability is critical. This vulnerability affects systems running Linux kernel versions that include the amd-xgbe driver and are processing network traffic through affected hardware, with the risk being proportional to network activity levels.
The fix implemented for CVE-2022-48743 addresses the vulnerability by modifying the driver's packet handling logic to proactively drop packets when length underflow conditions are detected rather than allowing the kernel to panic. This defensive programming approach aligns with the principle of fail-safe design and follows established security practices for handling malformed input data. The solution specifically involves adding validation checks to detect inconsistent hardware descriptors before attempting to process packet data, with the driver dropping problematic packets rather than allowing the kernel to terminate execution. This approach prevents the BUG_ON() condition from being triggered while maintaining network functionality for legitimate traffic. The fix is consistent with common network driver security practices and represents a standard response to buffer overflow and underflow conditions in kernel space code. The mitigation strategy directly addresses the CWE-129 vulnerability category related to improper validation of input data length and follows ATT&CK technique T1499.004 for network denial of service attacks, effectively neutralizing the threat while preserving system availability.