CVE-2025-38147 in Linux
الملخص
بحسب VulDB • 02/08/2026
Based on the kernel crash dump provided, here is an analysis of the issue.
### **Summary** The system crashed with a **NULL Pointer Dereference** (or similar invalid memory access) inside the Linux Security Module (LSM) stack during a `connect()` syscall. The crash occurred in the interaction between **SELinux**, **NetLabel**, and specifically the **Calipso** protocol handler.
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### **Key Details from the Call Trace**
1. **Triggering Event**: * A user-space process called `sys_connect` (`__x64_sys_connect`). * This triggered a security check via SELinux: `selinux_socket_connect`.
2. **Crash Location**: * The crash happened in `calipso_sock_setattr+0x56/0x80` at `net/netlabel/netlabel_calipso.c:557`. * This function is called from `netlbl_conn_setattr`, which was invoked by SELinux's netlabel helper (`selinux_netlbl_socket_connect_helper`).
3. **Root Cause Analysis**: * **SELinux** attempted to set NetLabel attributes on a socket during connection establishment. * It determined that the label type should be **Calipso**. * The kernel tried to configure the Calipso-specific options via `calipso_sock_setattr`. * Inside this function, it likely dereferenced a pointer (e.g., `sock->sk_protinfo`, `netlbl_domhsh_get()`, or a cached label structure) that was **NULL** or invalid.
4. **Common Causes for This Specific Crash**: * **Missing Calipso Configuration**: The kernel may have been compiled with NetLabel/Calipso support, but the necessary domain-to-label mapping (`netlbl_domhsh`) is not properly initialized or populated in userspace (via `auditd` or custom tools). * **Race Condition**: A socket was being connected while its associated security context was being removed or changed. * **Kernel Bug/Regression**: This could be a bug in the specific kernel version where `calipso_sock_setattr` does not properly check for NULL pointers before accessing Calipso-specific data structures.
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### **Recommended Actions**
#### 1. **Immediate Workaround (Disable NetLabel/Calipso)** If you do not require MAC labeling with Calipso, disable it to prevent the crash: * In SELinux policy or kernel boot parameters, ensure that netlabel is not forced for this socket type. * Alternatively, if using a container/virtualization environment, check if `net_label` capabilities are being incorrectly assigned.
#### 2. **Check Kernel Version** This looks like it could be related to known issues in older kernels (e.g., 5.x or early 6.x). Check your kernel version: ```bash uname -r ``` Search for bugs with keywords: `calipso_sock_setattr NULL pointer dereference selinux netlabel connect`
#### 3. **Verify NetLabel Configuration** If you are using SELinux with NetLabel/Calipso: * Ensure that `netlbl_domhsh` is properly populated. * Check `/var/log/messages` or `dmesg` for prior warnings about missing domain mappings.
#### 4. **Update Kernel/Patch** If this is a recent regression, check if there are upstream fixes in newer kernel versions (e.g., Linux 6.1+). The issue may have been fixed by adding NULL checks in `net/netlabel/netlabel_calipso.c`.
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### **Technical Deep Dive: Code Context** In `net/netlabel/netlabel_calipso.c`, around line 557, the function likely does something like: ```c static int calipso_sock_setattr(struct sock *sk, struct netlbl_lsm_secattr *secattr) {
// ... validation code ... // Likely crash point: accessing a pointer that wasn't initialized struct calipso_doi *doi_def = sk->sk_protinfo; if (!doi_def) return -EINVAL; // If this check is missing or bypassed, it crashes doi_def->calipso_setsockopt(sk, ...); } ```
If `sk` does not have a valid Calipso DOI definition attached (because SELinux tried to apply a label that doesn't map correctly), the pointer dereference fails.
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### **Conclusion** This is a **kernel panic due to NULL pointer dereference in SELinux/NetLabel integration**. It is most likely caused by: 1. A misconfigured NetLabel domain mapping for
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