CVE-2026-98911 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
dpaa2-switch: fix the error path in dpaa2_switch_rx()
In case of an error in dpaa2_switch_rx(), the dpaa2_switch_free_fd() function is called in order to free the FD. This is incorrect since the dpaa2_switch_free_fd() is intended to be used on Tx frame descriptors, meaning that it expects in the software annotation area of the FD data to find a valid skb pointer on which to call dev_kfree_skb().
Fix this by extracting the dma_unmap_page() from dpaa2_switch_build_linear_skb() directly into the dpaa2_switch_rx() function. This allows us to directly use free_pages() in case of an error before an SKB was created and kfree_skb() afterwards.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability identified within the Linux kernel's DPAA 2 switch driver involves a critical logic error in the receive path processing, specifically located in the dpaa2_switch_rx function. This issue stems from an incorrect handling of frame descriptors when errors occur during packet reception. In network drivers for high-performance hardware like the NXP Layerscape DPAA 2 platform, data flow is managed through Frame Descriptors or FDs which contain metadata and pointers to buffer memory. The driver distinguishes between transmit paths where buffers are allocated and prepared by software before transmission, and receive paths where buffers are provided by the hardware after packet arrival.
The core technical flaw lies in the error handling routine of dpaa2_switch_rx. When an anomaly or processing failure occurs during the reception of a frame, the original code invoked dpaa2_switch_free_fd to release resources associated with that descriptor. However, this function is designed exclusively for transmit-side operations where it expects specific software annotations within the FD structure, particularly a valid socket buffer pointer intended for deallocation via dev_kfree_skb. By applying this Tx-specific cleanup routine to an Rx context where such structures may not be initialized or relevant, the driver risks accessing invalid memory pointers or triggering undefined behavior due to mismatched resource management expectations.
This misalignment between expected and actual data states can lead to severe operational impacts including kernel panics, use-after-free conditions, or silent data corruption depending on the state of memory at the time of execution. In security terms, this represents a classic case of improper resource cleanup that could potentially be leveraged for denial-of-service attacks against the network subsystem. An attacker capable of inducing error conditions in packet processing might trigger these faulty code paths to destabilize the host system or escalate privileges if subsequent memory corruption allows control flow hijacking.
The remediation strategy involves refactoring the error handling logic within dpaa2_switch_rx to decouple DMA unmapping from socket buffer creation. By extracting dma_unmap_page directly into the receive function, developers ensure that hardware mappings are correctly released regardless of whether a socket buffer was successfully allocated. This allows for precise memory management using free_pages when no SKB exists and kfree_skb only after successful allocation. This approach aligns with best practices in kernel driver development by ensuring symmetric resource acquisition and release patterns tailored to the specific direction of data flow.
From an industry standards perspective, this vulnerability maps closely to CWE-401 which describes missing release of memory after effective usage leading to information leak or system instability. Additionally it relates to CWE-755 improper handling of unusual or unexpected input as the error path represents a non-standard execution branch that was not adequately secured against state mismatches. In terms of MITRE ATT&CK framework this could be categorized under T1498 network denial of service if exploited for system crashes, though primarily it falls under software quality assurance failures rather than direct attack vectors unless combined with other vulnerabilities.
Mitigation requires applying the upstream kernel patch that corrects these resource management routines in dpaa2_switch_rx administrators should ensure their systems are updated to include this fix particularly those running recent versions of Linux kernels on DPAA 2 hardware platforms. For organizations unable to immediately update, monitoring for unusual network stack behavior or system logs indicating memory allocation failures may provide early warning signs of exploitation attempts targeting these specific driver paths. Long-term improvements involve implementing stricter static analysis checks in CI pipelines to detect mismatches between Tx and Rx resource handling functions across all network drivers preventing similar architectural flaws from reaching production environments.