CVE-2023-53699 in Linux
Résumé
par VulDB • 14/06/2026
Based on the kernel panic log provided, here is a detailed analysis of the crash, its root cause, and potential solutions.
### 1. Crash Summary * **Architecture:** RISC-V (QEMU virt machine) * **Kernel Version:** `6.4.0-rc1` (Development/Release Candidate) * **Error Type:** Kernel Oops / Page Fault * **Faulting Address:** `0xff600000ffffd000` * **Bad Address Cause:** The address `0xff600000ffffd000` is **invalid/unmapped** in the kernel's virtual memory space. * **Triggering Function:** `__memcpy` (called from `memblock_double_array`)
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### 2. Root Cause Analysis
#### A. The Immediate Cause: Invalid Memory Access The CPU attempted to execute a `memcpy` operation at `__memcpy+0x60`, but the source or destination address (`0xff600000ffffd000`) was not mapped in the kernel's page tables. This resulted in a page fault during early boot.
#### B. The Context: `memblock_double_array` The call trace shows: ``` epc : __memcpy+0x60/0xf8 ra : memblock_double_array+0x192/0x248 ``` This indicates the crash occurred while the kernel was trying to **resize the memblock allocator's internal array**. The `memblock` subsystem manages early memory allocation before the full page allocator is ready. When it needs more space, it calls `memblock_double_array`, which may allocate new memory and copy existing data using `memcpy`.
#### C. Why is the Address Invalid? The address `0xff600000ffffd000` is highly suspicious: 1. **High Virtual Address:** In RISC-V 64-bit, kernel virtual addresses typically start at `0xffffffff80000000` (or similar, depending on `CONFIG_PAGE_OFFSET`). The address `0xff60...` is **below** the standard kernel text/data segment. 2. **Unmapped Region:** This address likely falls into a gap between the kernel image and the physical memory mapping, or it is a corrupted pointer. 3. **Possible Causes:** * **Stack Corruption:** The `s0` (frame pointer) and other registers show values like `ffffffff81403bd0`, which are in the kernel stack range. If the stack is corrupted, the pointer passed to `memcpy` could be garbage. * **Early Boot Memory Map Issue:** The device tree (DT) or QEMU memory configuration might be conflicting with the kernel's early memory setup. * **Bug in `memblock` Code:** Since this is an `-rc1` kernel, there may be a regression in how `memblock` handles memory resizing on RISC-V. * **Cache Coherency Issue:** On RISC-V, if memory is not properly marked as coherent or if cache operations are misaligned, it can lead to corrupted pointers.
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### 3. Key Observations from Registers * **`a0 : ff600000ffffd000`**: This is the first argument to `memcpy`, likely the **destination** or **source** buffer. This is the invalid address. * **`a1 : ffffffff80c0bcd8`**: Likely the source or destination pointer. This address is in the kernel text/data region (`0xffffffff80...`), which is valid. * **`a2 : 0000000000000c00`**: Length of the copy (3072 bytes). * **`status: 0000000200000100`**: Indicates an instruction access fault or similar, but the `badaddr` confirms it's a data access fault. * **`cause: 000000000000000f`**: On RISC-V, cause `0xf` (15) is an **Instruction Access Fault** or **Load/Store Access Fault** depending on the exception mode. Given the context, it's a load/store access fault due to unmapped memory.
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### 4. Recommended Solutions
#### A. Immediate Workarounds 1. **Boot with `memblock=debug` or `earlyprintk`:** Add these kernel parameters to get more context before the crash: ```bash memblock=debug earlyprintk ```
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