Executive Summary

CVE-2025-10823 is a null pointer dereference vulnerability in the fio tool (up to version 3.41) within the function str_buffer_pattern_cb in options.c. It occurs when the program parses a jobfile option 'buffer_pattern' without a value (e.g., 'buffer_pattern='), causing a NULL pointer to be passed to the function. The function then calls strlen() on this NULL pointer, leading to a segmentation fault and crashing the program. [1, 2, 3]

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Impact Analysis

This vulnerability can cause the fio program to crash due to a null pointer dereference, impacting the availability of the application. Since the attack must be performed locally, an attacker with local access can exploit this to cause denial of service by crashing fio. It does not affect confidentiality or integrity. [3]

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Detection Guidance

This vulnerability can be detected by testing the fio tool with a specially crafted jobfile that includes the option `buffer_pattern=` without a value, which triggers a null pointer dereference and causes a crash. Detection was performed using fuzz testing with AddressSanitizer (ASan) and UndefinedBehaviorSanitizer (UBSan) on an Ubuntu 22.04 system. To detect it, you can run fio with a jobfile containing `buffer_pattern=` and observe if the program crashes with a segmentation fault. Example command: `fio --filename=testfile --buffer_pattern=` (using a jobfile or command line option). Monitoring for segmentation faults or crash logs referencing `str_buffer_pattern_cb` or `strlen()` on NULL pointers can confirm the presence of the vulnerability. [2]

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Mitigation Strategies

Immediate mitigation steps include avoiding the use of the vulnerable fio versions up to 3.41 or refraining from specifying the `buffer_pattern` option without a value in jobfiles or command line. Since no official patch or internal fix is available yet, consider replacing fio with an alternative tool or applying external patches if available. Additionally, restrict local access to systems running fio to trusted users only, as exploitation requires local access. [3, 2]

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