CVE-2026-64582 in Linux
Tóm tắt
Bởi VulDB • 05/08/2026
Based on the crash trace provided, here is an analysis of the kernel panic/oops.
### **Summary** The system crashed in the `rxe_mmap` function (part of the Linux RDMA "Software RoCE" driver) while trying to map a page into user space via `remap_vmalloc_range`. The crash occurred inside `insert_page`, which is called by `vm_insert_page`.
### **Key Components** 1. **Driver:** `rxe` (RDMA over Converged Ethernet - Software implementation). 2. **Function Chain:** * User-space calls `mmap()` system call (`__x64_sys_mmap`). * VFS layer invokes the driver's mmap handler: `ib_uverbs_mmap`. * RDMA core dispatches to specific device implementation: `rxe_mmap`. * RXE tries to map a vmalloc'd page into user space: `remap_vmalloc_range` -> `vm_insert_page` -> `insert_page`. 3. **Crash Location:** `insert_page+0x8f/0x190`.
### **Analysis of the Crash**
#### **1. Likely Cause: Invalid Page Pointer or State** The function `insert_page()` is responsible for inserting a single page into a VMA (Virtual Memory Area). It expects a valid, pinned kernel page (`struct page *`). The crash suggests one of the following: * **Null/Invalid Page:** The `page` pointer passed to `vm_insert_page` might be invalid or NULL. However, KASAN would typically catch this earlier if it were a simple null dereference unless it's a use-after-free or corrupted structure. * **Page State Corruption:** The page struct itself might be corrupted (e.g., freed but still referenced). This is consistent with the presence of `kasan` in the call trace (`? kasan_save_alloc_info`, `? __kasan_slab_free`). KASAN detects memory errors, and its involvement suggests this crash was **triggered by a detected memory corruption** or occurred during/after such an event. * **Race Condition:** The page might have been freed concurrently while being mapped.
#### **2. Role of KASAN (Kernel Address Sanitizer)** The trace shows multiple `kasan` functions: * `? kasan_save_alloc_info+0x38/0x60`: This suggests that memory was recently allocated, and its info is being saved for error reporting. * `? __kasan_slab_free+0x7d/0xa0`: A slab object (likely the page or a related structure) has been freed.
**Interpretation:** It is highly probable that this is a **Use-After-Free (UAF)** bug in the RXE driver. The code attempted to map a page (`rxe_mmap`) after it had already been freed by another part of the system, or during cleanup where references were not properly managed.
#### **3. Why `insert_page` Crashed** Inside `insert_page()`, common operations include: * Checking if the page is valid. * Updating page table entries (PTEs). * Handling memory barriers and locks.
If the page pointer was dangling (UAF), dereferencing it to check flags or update PTEs would cause a general protection fault (#GP) or null pointer dereference, depending on what garbage value is in that memory location now. The `CR2` register (`0x7b1e00a24ac0`) indicates the address that caused the page fault (if it was a PF) or invalid access. Since this is an Oops and not necessarily a Page Fault (though CR2 is set), it might be a general protection fault due to accessing freed memory with specific patterns KASAN uses for detection.
### **Recommended Actions**
1. **Check Kernel Logs:** Look above the trace in `dmesg` or `/var/log/kern.log` for: * Explicit KASAN error messages (e.g., "BUG: KASAN: use-after-free"). These will give you the exact object that was freed and where it was allocated. * Any warnings from the RXE driver before the crash.
2. **Review RXE Driver Code:** Focus on `rxe_mmap` in `drivers/infiniband/sw/rxe/rxe_verbs.c`. Look for: * How pages are obtained and pinned (`get_user_pages`, etc.). * Reference counting of the memory regions (MRs - Memory Regions). * Cleanup paths where pages might be freed while still being mapped or in flight.
3. **Reproduce with KASAN Enabled:** If you can reproduce
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