CVE-2022-48940 in Linux
Zusammenfassung
von VulDB • 10.06.2026
Implied intent: The user is providing a Linux kernel crash log (likely a KASAN or general oops/panic trace) and implicitly asking for an analysis of the crash, its cause, and potential fixes. The presence of `bpf_trampoline` and `__x64_sys_nanosleep` suggests a BPF-related issue during a system call.
Safety evaluation: The user is asking for technical analysis of a kernel crash. This is a standard debugging request. There is no request to generate malware, exploit code, or bypass security controls. Analyzing a crash log is a defensive/operational task. The request is safe.
Response strategy: 1. **Identify the crash type**: The log shows a general kernel oops/panic trace. The `RIP` and `Code` section indicate a fault occurred in user-space code (`0x7f9e4831718d` is in the libc/shared library range, not kernel space). However, the trace shows `bpf_trampoline` on the stack, which is suspicious. 2. **Analyze the stack trace**: * `__x64_sys_nanosleep`: The system call being executed. * `bpf_trampoline_6442477838_0`: A BPF program was attached to this syscall (likely via `fentry`/`fexit` or `kprobe`/`kretprobe` on `sys_nanosleep`). * The crash happens *after* returning from the syscall or during the return path, but the `RIP` points to user space. This often indicates a **use-after-free** or **corruption** of user-space memory, or a BPF program that incorrectly modified user-space registers/memory. * Alternatively, the `RIP` might be a corrupted return address if the kernel stack was corrupted, but `0x7f9e...` is clearly a user-space address (likely `libc.so`). * The `RAX: ffffffffffffffffda` is a negative error code (`-22` = `EINVAL` or similar, depending on context, but `da` is `-22` in two's complement? `0xda` = 218, `-22` is `0xee`... wait. `0xffffffffffffffda` is `-42` (`-ERANGE`? No, `-42` is `-ERANGE`? Let's check: `-1` is `0xff`, `-22` is `0xee`. `0xda` is `-38`? `0xda` = 218. 256-218=38. So `-38` (`-EIO`? No, `-EIO` is `-5`. `-38` is `-E2BIG`? No. `-38` is `-E2BIG`? Let's check Linux error codes. `-38` is `-ENOSYS`? No. `-38` is `-E2BIG`? No. `-38` is `-E2BIG` is `-7`. `-38` is `-E2BIG`? No. `-38` is `-E2BIG`? Let's not guess the error code, it's likely not the root cause). * The key is `bpf_trampoline`. BPF programs running in kernel context must not access user memory directly without proper helpers (`copy_from_user`, etc.). If a BPF program attached to `sys_nanosleep` tries to access user-space memory incorrectly, it can cause a crash. * However, the `RIP` is in user space. This suggests the crash happened in user space, but the kernel trace shows the context. This could be a **page fault** in user space that was handled by the kernel, but the trace shows the kernel state *before* the fault? No, the trace is from the kernel's perspective. * Actually, `RIP: 0033:0x7f9e4831718d` with `Code:` showing x86 instructions suggests the CPU was executing user-space code when the fault occurred. But the stack trace shows kernel functions. This is contradictory unless the trace is from a **user-space crash** that was caught by the kernel (e.g., via `ptrace` or a signal handler), or the BPF program corrupted the user-space stack/registers. * Most likely: A BPF program attached to `sys_nanosleep` (via `fentry`/`fexit`) is buggy. It might be modifying user-space registers or memory incorrectly, leading to a crash in user space. Or, the BPF program is causing a kernel panic, and the `RIP` shown is misleading or from a different context. * Wait, the `RIP` is `0033:0x7f9e4831718d`. Segment `0033` is user-space code segment. This means the crash happened in user space. The kernel trace shows the call stack *at the time of the crash*. This implies the kernel was executing `sys_nanosleep`, called a BPF program, and then the CPU jumped to a user-space address that is invalid or caused a fault. * This is a classic symptom of a **BPF program returning a corrupted return address** or **modifying user-space registers** incorrectly. * The `bpf_trampoline` is a JIT-compiled stub that calls the BPF program. If the BPF program has a bug (e.g., invalid memory access, incorrect register manipulation), it can corrupt the state. * The `__x64_sys_nanosleep` is the syscall. The BPF program is likely attached via `BPF_PROG_TYPE_KPROBE` or `BPF_PROG_TYPE_TRACING` (fentry/fexit). * The crash is likely due to a **bug in the BPF program** attached to `sys_nanosleep`.
3. **Formulate the response**: * State that the crash occurred in user space (`RIP` in `0x7f9e...` range) but the kernel trace shows a BPF program (`bpf_trampoline`) was active during the `sys_nanosleep` syscall. * Explain that this pattern strongly suggests a **buggy BPF program** attached to the `sys_nanosleep` syscall (likely via `fentry`/`fexit` or `kprobe`). * The BPF program may be corrupting user-space registers, stack, or return addresses. * Advise the user to: * Identify the BPF program attached to `sys_nanosleep`. * Check the BPF program's code for errors (e.g., invalid memory access, incorrect register usage). * Use `bpftool prog show` or `bpftrace` to find the attached program. * Temporarily unload the BPF program to see if the crash stops. * Review BPF verifier logs for the program.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.