CVE-2023-52745 in Linux
Zusammenfassung
von VulDB • 01.06.2026
Implied intent: The user is providing a Linux kernel crash dump (Oops/BUG) and implicitly asking for an analysis of the cause, the vulnerable function, and potential mitigation or root cause identification.
**1. Analysis of the Crash Dump**
* **Crash Type:** The dump shows a `Call Trace` starting from `skb_clone`. This is a classic kernel panic or Oops scenario involving network packet handling. * **Key Function:** `skb_clone+0x55/0xd0` is the first function in the trace. This is the most critical clue. `skb_clone` is used to create a copy of a `sk_buff` (socket buffer) structure. * **Context:** The trace flows through IPv6 UDP sending: `udp_v6_send_skb` -> `ip6_send_skb` -> `ip6_finish_output` -> `ip6_finish_output2` -> `skb_clone`. This indicates the crash occurred while the kernel was trying to send a UDP packet over IPv6. * **Registers:** * `RIP: 0x7f9374f1ed14`: This is a user-space address (high memory address, likely part of a shared library or executable). This suggests the crash was triggered by a system call from user space (`__sys_sendto`). * `RAX: ffffffffffffffda`: This is `-42` in two's complement, which corresponds to the error code `-ENOPROTOOPT` (Protocol not available) or similar, but in the context of a crash, it might be garbage or a specific error code passed back. However, the crash itself is in kernel space. * `DR6: 00000000fffe0ff0`: Debug register, often set by hardware breakpoints or kernel debugging features, but here it might just be part of the context.
**2. Root Cause Identification**
The crash in `skb_clone` is highly suspicious. `skb_clone` is a very basic, well-tested function. A crash here usually implies one of the following:
* **Corrupted `sk_buff` Pointer:** The most common cause. The kernel is trying to clone an `sk_buff` structure that has been corrupted (e.g., use-after-free, double free, or memory corruption elsewhere). The pointer passed to `skb_clone` is invalid or points to freed memory. * **Memory Corruption:** A bug elsewhere in the kernel or a driver has overwritten memory adjacent to the `sk_buff` structure, corrupting its internal pointers or size fields. * **Race Condition:** A concurrent modification of the `sk_buff` structure while it is being cloned. * **Kernel Bug:** A rare bug in `skb_clone` itself, but this is less likely given its simplicity.
**3. Vulnerability Assessment**
* **Potential CVE:** This pattern (crash in `skb_clone` during network packet processing) is often associated with **Use-After-Free (UAF)** vulnerabilities in network drivers or protocol handlers. An attacker might be able to trigger this by sending a specially crafted UDP packet over IPv6. * **Severity:** High. A kernel panic can lead to Denial of Service (DoS). If the corruption can be controlled, it might lead to arbitrary code execution (privilege escalation).
**4. Mitigation and Next Steps**
* **Immediate Mitigation:** * **Disable IPv6:** If IPv6 is not required, disable it to prevent the code path from being executed. * **Update Kernel:** Check if there is a newer kernel version that fixes known bugs in `skb_clone` or related network code. * **Network Filtering:** Use `iptables` or `nftables` to block suspicious UDP traffic on IPv6. * **Debugging:** * **Enable Kernel Debugging:** Compile the kernel with `CONFIG_DEBUG_SLAB`, `CONFIG_SLAB_FREELIST_HARDENED`, and `CONFIG_KASAN` (Kernel Address Sanitizer) to get more detailed information about memory corruption. * **Analyze Core Dump:** If a core dump was generated, analyze it with `crash` utility to get more context about the corrupted `sk_buff`. * **Check Logs:** Look for other warnings or errors in `dmesg` or `/var/log/syslog` around the time of the crash.
**5. Conclusion**
The crash is likely caused by a **Use-After-Free** or **memory corruption** issue in the kernel's network stack, specifically when handling IPv6 UDP packets. The `skb_clone` function is receiving a corrupted or invalid `sk_buff` pointer. This is a serious bug that could be exploited for DoS or potentially privilege escalation. Immediate mitigation involves disabling IPv6 or updating
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