CVE-2024-36919 in Linux
Zusammenfassung
von VulDB • 16.05.2026
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:** **BNX2FC** (Broadcom NetXtreme II Fibre Channel over Ethernet driver). * **Trigger:** The crash occurred during **I/O memory DMA freeing** (`__iommu_dma_free`) while cleaning up a Fibre Channel session. * **Context:** The driver was handling an rport event (`bnx2fc_rport_event_handler`) and attempting to free resources for a session (`bnx2fc_free_session_resc`).
### **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]
process_one_work+0x1e8/0x3c0 worker_thread+0x50/0x3b0 ``` * **Root Cause Location:** The crash happens in `__iommu_dma_free`, which is called from `bnx2fc_free_session_resc`. * **Likely Bug:** This typically indicates a **use-after-free**, **double-free**, or **invalid DMA handle** being passed to the IOMMU subsystem. The driver may be trying to free DMA memory that was already freed, corrupted, or never properly allocated.
### **3. Common Causes for BNX2FC Crashes** 1. **Driver Bug:** A known bug in the `bnx2fc` driver version interacting with the specific kernel version. 2. **Firmware Issue:** Outdated or buggy firmware on the Broadcom NetXtreme II adapter. 3. **Hardware Fault:** Rare, but possible memory corruption on the NIC. 4. **Race Condition:** A race between session teardown and I/O completion.
### **4. Recommended Troubleshooting Steps**
#### **A. Immediate Mitigation** 1. **Update Kernel:** Check if a newer kernel version fixes this issue. Many `bnx2fc` bugs were resolved in later 5.x/6.x kernels. 2. **Update Driver/Firmware:** * Update the `bnx2fc` driver to the latest version from Broadcom or your distribution. * Update the NIC firmware using `ethtool -S` or Broadcom’s firmware update tools. 3. **Disable BNX2FC (If Not Critical):** * If Fibre Channel over Ethernet (FCoE) is not essential, blacklist the module: ```bash echo "blacklist bnx2fc" | sudo tee /etc/modprobe.d/blacklist-bnx2fc.conf sudo update-initramfs -u ``` * Reboot to verify stability.
#### **B. Debugging & Logging** 1. **Enable Kernel Debugging:** * Reboot with `debug` or `loglevel=7` in the kernel boot parameters to get more verbose logs. 2. **Check dmesg for Earlier Warnings:** * Look for errors in `bnx2fc` or `libfc` before the crash (e.g., timeouts, link flaps). 3. **Verify IOMMU Settings:** * If using IOMMU (VT-d/AMD-Vi), try disabling it temporarily in the bootloader (`intel_iommu=off` or `amd_iommu=off`) to see if the crash persists. This can help isolate IOMMU-related DMA issues.
#### **C. Long-Term Solutions** 1. **Switch to Alternative FCoE Driver:** * Consider using `cxgb4i` (Chelsio) or `bnx2i` (Broadcom iSCSI) if applicable, or migrate to native Fibre Channel (`qla2xxx`) if hardware allows. 2. **Report the Bug:** * If this is a recent kernel, report the bug to the Linux kernel mailing list (LKML) or your distribution’s bug tracker, including the full `dmesg` output and kernel version.
### **5. Kernel Version Check** Run the following to identify your kernel version:
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