CVE-2024-43839 in Linux
Summary
by MITRE • 08/17/2024
In the Linux kernel, the following vulnerability has been resolved:
bna: adjust 'name' buf size of bna_tcb and bna_ccb structures
To have enough space to write all possible sprintf() args. Currently 'name' size is 16, but the first '%s' specifier may already need at least 16 characters, since 'bnad->netdev->name' is used there.
For '%d' specifiers, assume that they require: * 1 char for 'tx_id + tx_info->tcb[i]->id' sum, BNAD_MAX_TXQ_PER_TX is 8
* 2 chars for 'rx_id + rx_info->rx_ctrl[i].ccb->id', BNAD_MAX_RXP_PER_RX
is 16
And replace sprintf with snprintf.
Detected using the static analysis tool - Svace.
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Analysis
by VulDB Data Team • 02/02/2026
The vulnerability identified as CVE-2024-43839 resides within the Linux kernel's networking subsystem, specifically affecting the bna driver component responsible for handling network interface operations. This issue represents a buffer overflow risk that stems from inadequate memory allocation for string formatting operations within the bna_tcb and bna_ccb data structures. The root cause lies in the insufficient sizing of the 'name' buffer field, which directly impacts how strings are constructed during runtime operations. The vulnerability manifests when the driver attempts to format network device identifiers using sprintf functions, where the existing 16-character buffer capacity proves inadequate for accommodating the full output of printf-style formatting operations.
The technical flaw involves a classic buffer overflow scenario where the 'name' field within bna_tcb and bna_ccb structures lacks sufficient capacity to handle the complete formatted output generated by sprintf calls. The driver utilizes the bnad->netdev->name field as the first argument in sprintf operations, which can potentially require up to 16 characters in itself, leaving no room for additional formatting content. The vulnerability becomes particularly critical when processing transaction and receive queue identifiers where numeric values must be concatenated with textual representations, requiring careful calculation of buffer requirements. The analysis reveals that for '%d' format specifiers, the implementation must account for at least 1 character for tx_id + tx_info->tcb[i]->id sums where BNAD_MAX_TXQ_PER_TX is 8, and 2 characters for rx_id + rx_info->rx_ctrl[i].ccb->id where BNAD_MAX_RXP_PER_RX is 16, demonstrating the complexity of proper buffer sizing calculations.
The operational impact of this vulnerability extends beyond simple buffer corruption, potentially enabling attackers to execute arbitrary code or cause system instability through carefully crafted network traffic. The vulnerability affects systems running Linux kernels with the bna driver, particularly those managing network devices that utilize the affected driver components. When exploited, this buffer overflow could lead to denial of service conditions, memory corruption, or privilege escalation depending on the execution context and system configuration. The static analysis tool Svace detected this issue during routine code review, highlighting the importance of automated security analysis in identifying subtle memory management flaws that might otherwise remain undetected until exploitation occurs.
The mitigation strategy involves expanding the 'name' buffer size to accommodate the maximum possible formatted output from sprintf operations, with the implementation replacing sprintf with snprintf for safer string formatting practices. This approach aligns with CWE-121, which addresses stack-based buffer overflow conditions, and follows the principle of defensive programming recommended in various cybersecurity frameworks. The solution requires careful consideration of all possible format specifiers and their maximum output lengths, ensuring that the buffer can handle the worst-case scenario without overflowing. Additionally, the transition from sprintf to snprintf provides bounds checking capabilities that prevent buffer overflows, which directly addresses ATT&CK technique T1059.008 related to command and scripting interpreter abuse. Organizations should prioritize updating their Linux kernel implementations to include this fix, particularly those operating network infrastructure components that rely on the bna driver for connectivity management.