CVE-2024-36919 in Linux
Riassunto
di VulDB • 16/06/2026
Based on the kernel log provided, here is an analysis of the crash, its likely cause, and recommended troubleshooting steps.
### **1. Summary of the Issue** * **Error Type:** Kernel Oops/Panic (indicated by `Call Trace` and `end trace`). * **Subsystem:** Fibre Channel over Ethernet (FCoE) / BNX2FC Driver. * **Trigger:** The crash occurred during **I/O memory DMA freeing** (`__iommu_dma_free`) while cleaning up a session resource (`bnx2fc_free_session_resc`). * **Context:** The driver was handling an RPort event (`bnx2fc_rport_event_handler`) via a workqueue (`fc_rport_work`).
### **2. Key Call Trace Analysis** ``` __iommu_dma_free+0x96/0x100 bnx2fc_free_session_resc+0x67/0x240 [bnx2fc]
bnx2fc_upload_session+0xce/0x100 [bnx2fc]
bnx2fc_rport_event_handler+0x9f/0x240 [bnx2fc]
fc_rport_work+0x103/0x5b0 [libfc]
``` * **`__iommu_dma_free`**: The kernel is trying to free DMA-mapped memory associated with an IOMMU. This suggests a **use-after-free**, **double-free**, or **invalid DMA handle** issue. * **`bnx2fc_free_session_resc`**: The BNX2FC driver is freeing resources for an FC session. * **`bnx2fc_upload_session`**: This function is called during session setup/upload. It appears that during an RPort event (e.g., link down, login failure, or topology change), the driver attempted to free resources but encountered an invalid state. * **`bnx2fc_rport_event_handler`**: The crash was triggered by an event on an FC remote port (RPort).
### **3. Likely Causes** 1. **Race Condition in BNX2FC Driver**: * The driver may be freeing DMA memory that is still in use by hardware or another thread. * A common scenario: An RPort event (e.g., link down) triggers cleanup, but pending I/O or DMA descriptors are still being processed.
2. **Invalid DMA Handle**: * The DMA handle passed to `__iommu_dma_free` might be corrupted, already freed, or never properly allocated.
3. **Bug in Specific Kernel Version**: * This is a known class of bugs in older versions of the `bnx2fc` driver. Check if your kernel version is affected by known CVEs or bug fixes related to `bnx2fc` DMA handling.
4. **Hardware/Firmware Issue**: * Corrupted firmware on the QLogic/Broadcom adapter (BNX2FC is often associated with Broadcom NetXtreme-C/E adapters or QLogic adapters using the bnx2fc driver).
### **4. Recommended Troubleshooting Steps**
#### **A. Immediate Workaround** 1. **Disable FCoE/BNX2FC if not needed**: If you do not require FCoE, unload the module to prevent further crashes: ```bash sudo rmmod bnx2fc ``` *(Note: This will break any FCoE storage connections.)*
2. **Update Kernel/Driver**: * Check if a newer kernel version contains fixes for `bnx2fc` DMA issues. * Look for commits related to `bnx2fc` in the Linux kernel git log, especially around `__iommu_dma_free` and `bnx2fc_free_session_resc`.
#### **B. Diagnostic Steps** 1. **Check Kernel Version**: ```bash uname -r ``` Search for known bugs in your specific kernel version.
2. **Check dmesg for Earlier Errors**: Look for warnings or errors from `bnx2fc`, `libfc`, or `i40e` (if using i40e for FCoE offload) before the crash. ```bash dmesg | grep -i bnx2fc dmesg | grep -i i40e ```
3. **Update Firmware**: * Update the firmware for your network adapter (Broadcom NetXtreme-C/E or QLogic). * Ensure the `bnx2fc` driver version matches the firmware expectations.
4. **Test with Different Kernel**:
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