CVE-2023-54104 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
mtd: rawnand: fsl_upm: Fix an off-by one test in fun_exec_op()
'op-cs' is copied in 'fun->mchip_number' which is used to access the 'mchip_offsets' and the 'rnb_gpio' arrays. These arrays have NAND_MAX_CHIPS elements, so the index must be below this limit.
Fix the sanity check in order to avoid the NAND_MAX_CHIPS value. This would lead to out-of-bound accesses.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/03/2026
The vulnerability identified as CVE-2023-54104 resides within the Linux kernel's MTD (Memory Technology Device) subsystem, specifically in the raw NAND flash driver implementation for Freescale UPM (Unified Programming Module) controllers. This issue manifests as an off-by-one error in the function fun_exec_op() which handles execution of NAND operations. The flaw occurs when processing chip select operations where the 'op-cs' value is copied into 'fun->mchip_number' field, creating a potential pathway for memory access violations.
The technical implementation of this vulnerability stems from improper bounds checking during NAND chip addressing operations. The function processes 'op-cs' values that are intended to represent chip select identifiers for NAND flash devices, but fails to validate that these values remain within acceptable bounds. The affected arrays 'mchip_offsets' and 'rnb_gpio' are dimensioned to accommodate NAND_MAX_CHIPS elements, meaning valid indices should range from 0 to NAND_MAX_CHIPS-1. However, the flawed validation logic permits the value NAND_MAX_CHIPS itself to pass through, creating a scenario where array access attempts occur beyond the allocated memory boundaries.
This memory access violation represents a classic buffer overflow condition that can potentially lead to system instability, data corruption, or privilege escalation depending on the execution context. The vulnerability affects systems utilizing Freescale UPM-based NAND controllers where multiple NAND chips are configured in a single device, making it particularly relevant in embedded systems, industrial computing platforms, and automotive applications that rely on such flash storage architectures. The flaw demonstrates characteristics consistent with CWE-129, which addresses improper validation of array indices, and may enable techniques described in ATT&CK tactic TA0004 (Privilege Escalation) through potential memory corruption exploitation.
The operational impact of this vulnerability extends beyond simple memory access violations to potentially compromise system integrity in environments where NAND flash storage serves as primary or secondary storage media. Systems utilizing multiple NAND chips in configurations that exceed the bounds checking limitations could experience unexpected behavior including kernel panics, data loss, or denial of service conditions. The fix implemented addresses the core validation issue by modifying the sanity check to exclude the NAND_MAX_CHIPS value from valid index range, thereby preventing out-of-bounds memory accesses that could otherwise be exploited by malicious actors or result in system instability during normal operation.
Mitigation strategies for this vulnerability should prioritize immediate kernel updates from trusted sources to ensure the patched version resolves the bounds checking error. System administrators should also consider implementing additional monitoring for unusual memory access patterns or kernel panics that might indicate exploitation attempts. The fix aligns with security best practices for memory safety and follows established protocols for addressing buffer overflow vulnerabilities in kernel space operations. Organizations utilizing embedded systems with Freescale UPM NAND controllers should conduct thorough testing of updated kernel versions to verify proper functionality while ensuring that the patched implementation maintains backward compatibility with existing hardware configurations.