CVE-2025-40238 in Linux
Сводка
по VulDB • 16.06.2026
Based on the stack trace provided, here is an analysis of the issue:
### **Summary** This is a **kernel crash (Oops/Panic)** occurring in the **Mellanox ConnectX (mlx5) InfiniBand/RoCE driver** (`mlx5_ib`) during the initialization of a slave port. The crash happens while processing a **devlink eswitch mode change** event.
The root cause is likely a **race condition** or **null pointer dereference** in `mlx5_ib_bind_slave_port()` when it tries to replay MP (Multi-Path) events or bind a port that is in an inconsistent state.
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### **Stack Trace Breakdown**
1. **Trigger:** * `devlink_nl_eswitch_set_doit()` → `mlx5_devlink_eswitch_mode_set()` * A user-space tool (e.g., `devlink`, `iproute2`) changed the eswitch mode (e.g., from `switchdev` to `legacy` or vice versa). * This triggers `esw_mode_change()` → `mlx5_rescan_drivers_locked()` → `add_adev()` → `auxiliary_bus_probe()`.
2. **Probe Path:** * `auxiliary_bus_probe()` calls the driver's probe function: `mlx5r_probe()` → `__mlx5_ib_add()` → `mlx5_ib_stage_init_init()`.
3. **Crash Point:** * `mlx5_ib_stage_init_init()` calls `mlx5_ib_bind_slave_port()`. * Inside `mlx5_ib_bind_slave_port()`, it calls `mlx5_core_mp_event_replay()` → `mlx5_blocking_notifier_call_chain()` → `notifier_call_chain()`. * **RIP:** `0x7f27bc91b13a` (This is a **user-space address**, which is highly unusual for a kernel crash. See "Critical Anomaly" below).
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### **Critical Anomaly: User-Space RIP** The `RIP: 0033:0x7f27bc91b13a` indicates the CPU was executing code in **user space** when the crash occurred. This is **not a standard kernel oops**.
Possible explanations: 1. **KVM/QEMU Guest Crash:** If this is a VM, the guest kernel crashed, and the host is showing the guest's user-space RIP. 2. **Corrupted Stack/Return Address:** The kernel stack is corrupted, and the return address is garbage. 3. **User-Space Triggered Kernel Panic:** A user-space program caused a kernel panic, and the RIP shown is from the syscall entry point (`__x64_sys_sendto` → `netlink_sendmsg` → ... → kernel crash). However, the RIP should be in kernel space (`0x...` starting with `0xffffffff...`). The fact that it's `0x7f...` suggests this might be a **guest kernel** crash being reported by a host tool, or the stack trace is from a **user-space crash** that invoked a kernel fault.
> **Note:** In most Linux kernel crash dumps, the RIP is in kernel space (`0xffffffff...`). A user-space RIP in a kernel stack trace is a strong indicator that this is either: > - A **KVM guest** crash. > - A **corrupted dump**. > - A **user-space application** that crashed while holding a lock or in a signal handler, and the stack trace is misinterpreted.
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### **Likely Root Cause in Kernel Code**
If we ignore the RIP anomaly and focus on the kernel code path:
#### **1. Race Condition in `mlx5_ib_bind_slave_port()`** The function `mlx5_ib_bind_slave_port()` is called during eswitch mode change. It tries to bind a slave port and replay MP events. If the port is not fully initialized or if the hardware state is inconsistent, this can lead to a null pointer dereference or invalid memory access.
#### **2. Notifier Chain Issue** `mlx5_core_mp_event_replay()` calls `mlx5_blocking_notifier_call_chain()`. If a notifier callback is invalid or the notifier list is corrupted, this can crash.
#### **3. Eswitch Mode Change Race** Changing eswitch mode while ports are being probed or unprobed can lead to races. The `mlx5_rescan_drivers_locked()` function is supposed to handle this, but if a port is in an intermediate state, `mlx5_ib_bind_slave_port()` may fail.
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### **Recommended Actions**
1. **Check Kernel Version:** - This issue may be fixed in newer kernels. Check if your kernel version is
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