CVE-2023-52793 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
samples/bpf: syscall_tp_user: Fix array out-of-bound access
Commit 06744f24696e ("samples/bpf: Add openat2() enter/exit tracepoint to syscall_tp sample") added two more eBPF programs to support the openat2() syscall. However, it did not increase the size of the array that holds the corresponding bpf_links. This leads to an out-of-bound access on that array in the bpf_object__for_each_program loop and could corrupt other variables on the stack. On our testing QEMU, it corrupts the map1_fds array and causes the sample to fail:
# ./syscall_tp prog #0: map ids 4 5 verify map:4 val: 5 map_lookup failed: Bad file descriptor
Dynamically allocate the array based on the number of programs reported by libbpf to prevent similar inconsistencies in the future
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/05/2026
This vulnerability resides within the Linux kernel's eBPF sample implementation, specifically in the syscall_tp_user sample that handles system call tracepoints. The issue manifests as an array out-of-bounds access condition that occurs when the openat2() syscall enter/exit tracepoint programs are added to the sample. The root cause stems from a fundamental mismatch between the statically allocated array size and the actual number of programs that libbpf reports during program iteration. This discrepancy creates a critical memory corruption scenario where the bpf_object__for_each_program loop attempts to access memory beyond the allocated array boundaries, potentially overwriting adjacent stack variables.
The technical flaw represents a classic buffer overflow vulnerability with implications for memory safety and program integrity. When the code processes the additional eBPF programs for openat2() syscalls, it fails to dynamically adjust the array size that stores bpf_links corresponding to these programs. This misalignment allows the loop to traverse beyond the originally allocated memory space, leading to stack corruption that manifests as map lookup failures and bad file descriptor errors. The vulnerability directly relates to CWE-121, which addresses stack-based buffer overflow conditions, and demonstrates how improper array sizing can create exploitable memory corruption scenarios.
The operational impact of this vulnerability extends beyond simple program failure, potentially compromising the stability and reliability of eBPF tracing operations within the kernel. When the stack corruption occurs during execution, it affects not only the immediate functionality but also disrupts the proper mapping of file descriptors and program verification processes. The specific manifestation observed in the QEMU testing environment shows how corrupted map1_fds array contents lead to verification failures and ultimately cause the sample application to terminate prematurely. This type of memory corruption can be particularly dangerous in production environments where eBPF programs are used for security monitoring, network traffic analysis, or system performance tracing.
The recommended mitigation strategy involves implementing dynamic array allocation that scales based on the actual number of programs reported by libbpf during program iteration. This approach directly addresses the root cause by eliminating the static sizing assumption and ensuring memory allocation matches the runtime program count. The fix aligns with best practices for memory management in kernel space programming and follows established security principles outlined in various cybersecurity frameworks including those referenced in ATT&CK framework's system hardening categories. By adopting dynamic allocation, the codebase becomes more resilient to future modifications and additions of eBPF programs while maintaining proper memory boundaries and preventing similar out-of-bounds access scenarios that could potentially be exploited for privilege escalation or denial of service attacks.