CVE-2024-56551 in Linux
Zusammenfassung
von VulDB • 14.05.2026
Based on the kernel log snippet provided, here is an analysis of the issue:
### **Summary** This is a **KASAN (Kernel Address Sanitizer)** report indicating a **use-after-free** or **invalid memory access** in the AMDGPU driver (`amdgpu`) during GPU scheduler initialization. The crash occurs in user-space code (`0x7ffff7b14f67`) triggered by a system call, but the root cause is traced to kernel memory allocation in `drm_sched_init`.
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### **Key Details**
#### **1. The Crash** - **RIP**: `0x7ffff7b14f67` (User-space address, likely inside a library like `libdrm` or the application itself). - **RAX**: `0xffffffffffffda` → This is a **negative error code** (specifically `-26` or `-EINVAL` in some contexts, but often KASAN reports show `0xffffffffffffda` as a poisoned value or error return). However, in this context, it’s more likely that the user-space program received an error from a syscall (e.g., `ioctl`) and crashed while handling it. - **ORIG_RAX**: `0x0000000000000003` → This corresponds to **syscall number 3** on x86_64, which is **`read()`**. - **Wait**: Syscall 3 is `read()`. But GPU drivers typically use `ioctl()` (syscall 16). Let’s double-check: - On x86_64, `ioctl` is syscall **16** (`0x10`). - `read` is syscall **0** (`0x0`). - `write` is syscall **1** (`0x1`). - `open` is syscall **2** (`0x2`). - `close` is syscall **3** (`0x3`). - **Correction**: `ORIG_RAX: 0x0000000000000003` means the syscall was **`close()`**. - This suggests the user-space application was closing a file descriptor (likely a DRM device node like `/dev/dri/card0`) when the crash occurred.
#### **2. The Kernel Trace (Allocation Site)** KASAN is reporting where the problematic memory was **allocated**: - **Task**: 383 - **CPU**: 7 - **Time**: 26.880319s after boot - **Call Chain**: 1. `kmalloc_trace_noprof` → Memory allocation 2. `drm_sched_init` → DRM scheduler initialization 3. `amdgpu_device_init` → AMDGPU device initialization 4. `amdgpu_driver_load_kms` → AMDGPU KMS driver load 5. `amdgpu_pci_p...` → PCI probe (truncated)
This indicates that during the **initialization** of the AMDGPU driver, a memory block was allocated for the GPU scheduler.
#### **3. The Problem** - KASAN is detecting that this allocated memory is being **accessed after it was freed** (use-after-free) or is being accessed **out of bounds**. - The crash happens in user-space (`RIP: 0x7ffff7b14f67`) during a `close()` syscall. This is unusual because `close()` should not directly access kernel memory allocated during init unless: - The DRM device node is being closed, triggering cleanup code in the kernel. - The cleanup code accesses the freed scheduler memory. - The user-space application is crashing because it received a signal (e.g., `SIGSEGV`) from the kernel due to the invalid access.
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### **Likely Root Cause** 1. **Use-After-Free in AMDGPU Scheduler**: - The GPU scheduler (`drm_sched`) is initialized during driver load. - When the DRM device is closed (`close()` syscall), the driver may free the scheduler resources. - If there’s a race condition or a dangling pointer, the kernel might access freed memory during cleanup, triggering KASAN. - The user-space application crashes because the kernel sends a signal (e.g., `SIGBUS` or `SIGSEGV`) due to the invalid memory access.
2. **Bug in `amdgpu` Driver**: - This is likely a bug in the AMDGPU driver’s scheduler cleanup code. - Common causes: - Freeing the scheduler before all references are dropped. - Accessing scheduler memory after it’s been freed during device removal.
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