CVE-2026-80779 in Linux
Summary
by MITRE • 09/04/2026
In the Linux kernel, the following vulnerability has been resolved:
net/ionic: avoid OOB TX partner lookup for hwstamp RXQ
The dedicated hardware timestamp RX queue is allocated with q->index equal to lif->ionic->nrxqs_per_lif. The normal txqcqs array only contains the regular queue pairs, so using that index to set rxq->partner can read one entry past txqcqs[] and then write through the derived
pointer. Only link RX/TX partners for normal queue-pair indexes. Leave the hwstamp RX queue unpaired, and make the XDP_TX path abort cleanly if an RX queue has no TX partner.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in the Linux kernel network driver net/ionic involves a critical out-of-bounds memory access issue within the hardware timestamp receive queue handling logic. This flaw arises from an incorrect assumption regarding the indexing and pairing of transmit and receive queues. Specifically, when allocating resources for the dedicated hardware timestamp RX queue, the system assigns it an index value equal to nrxqs_per_lif, which represents the total count of normal receive queues per lifecycle object. However, the underlying txqcqs array, which stores references to regular queue pairs used for standard data transmission and reception, only contains entries corresponding to these normal queue-pair indexes. Consequently, attempting to use this specific index to look up a partner transmit queue results in accessing memory beyond the allocated bounds of the txqcqs array.
From a technical perspective, this out-of-bounds read occurs when the driver attempts to set rxq->partner by dereferencing an invalid pointer derived from the oversized index. This operation not only reads one entry past the end of the valid data structure but also writes through the derived pointer if subsequent logic proceeds without proper validation. Such memory corruption can lead to unpredictable system behavior, including kernel panics, data integrity issues, or potential privilege escalation depending on what lies in the adjacent memory space and how it is utilized by other subsystems. The root cause is fundamentally a lack of boundary checking for special-purpose queues that do not follow the standard RX/TX pairing model used for regular network traffic processing.
The operational impact of this vulnerability extends beyond simple stability concerns. By allowing an out-of-bounds access during queue partner lookup, the driver compromises the integrity of kernel memory structures associated with network interface management. An attacker or a malformed packet stream could potentially trigger this code path to cause a denial of service by crashing the host system. Furthermore, if the adjacent memory contains sensitive data or executable code, there is a theoretical risk of information disclosure or arbitrary code execution, although exploitation would require precise knowledge of kernel layout and specific triggering conditions related to hardware timestamping features being enabled on affected network interfaces.
To mitigate this vulnerability, the fix involves restructuring how queue partners are assigned for special queues like the hardware timestamp RXQ. The solution explicitly avoids linking these specialized queues to TX counterparts since they do not participate in standard bidirectional data flow patterns that require partner synchronization. Instead, the driver now ensures that only normal queue-pair indexes undergo the partner lookup process. For the hwstamp RX queue, which is left unpaired, additional safeguards are implemented within the XDP_TX path to detect when an RX queue lacks a valid TX partner and abort cleanly rather than attempting invalid memory operations. This approach aligns with secure coding practices by enforcing strict bounds checking and separating special-purpose hardware handling from general network stack logic.
This issue maps directly to CWE-787, which describes out-of-bounds write vulnerabilities resulting from improper validation of array indices or pointer arithmetic. In the context of attack patterns, this flaw could be leveraged within ATT&CK technique T1059, specifically through command and script interpreters if an attacker can influence queue configuration via privileged interfaces, though more commonly it serves as a vector for local privilege escalation (T1068) or denial of service (T1499) by inducing kernel crashes. System administrators should ensure that the Linux kernel is updated to include patches addressing this net/ionic driver flaw, particularly on systems utilizing Intel I350 or similar network adapters where hardware timestamping features are active. Regular auditing of kernel logs for oops messages related to network drivers can also help in detecting potential exploitation attempts before they lead to full system compromise.