CVE-2024-53178 in Linux
Zusammenfassung
von VulDB • 22.05.2026
Implied User Intent: The user has pasted a Linux kernel crash dump (Oops/Panic trace) and implicitly wants to know what went wrong, why it happened, and how to fix or investigate it further.
Key Technical Concepts: 1. **Kernel Oops/Panic**: The system encountered a fatal error in kernel space. 2. **`umount_check`**: The function where the crash occurred. This is part of the VFS (Virtual File System) layer, specifically during the unmounting process. 3. **`d_walk`**: The function being called when the crash happened. It walks the dentry cache (directory entry cache). 4. **`shrink_dcache_for_umount`**: The context. The kernel is trying to shrink the dcache because a filesystem is being unmounted. 5. **`cifs_kill_sb`**: The superblock being killed belongs to the CIFS (Common Internet File System) driver. This indicates the crash happened while unmounting a CIFS/SMB share. 6. **`RIP: 0033:0x7f23bfb93ae7`**: The instruction pointer. The `0033` segment selector indicates user-space code, but this is likely a return address from a syscall or a corrupted stack. However, the actual crash is in kernel space (`umount_check`). The `RIP` shown at the bottom is often the return address to user space after the syscall failed. 7. **`CR2: 0000556de4a6f808`**: This is the faulting address for a page fault. If this was a NULL pointer dereference, CR2 would be 0. Here, it's a specific address, suggesting a use-after-free, invalid pointer, or corrupted memory. 8. **`RAX: 0000000000000000`**: RAX is zero. This is often the value being dereferenced or returned. If the code expected a valid pointer in RAX and tried to dereference it, this would cause a crash.
Step-by-Step Analysis: 1. **Identify the Crash Location**: The crash is in `umount_check+0xd0/0x100`. 2. **Identify the Context**: The call trace shows `shrink_dcache_for_umount` -> `generic_shutdown_super` -> `kill_anon_super` -> `cifs_kill_sb`. This confirms the crash is happening during the unmount of a CIFS filesystem. 3. **Analyze the Call Trace**: * `entry_SYSCALL_64_after_hwframe`: System call entry. * `do_syscall_64`: System call handler. * `syscall_exit_to_user_mode`: Exiting syscall. * `task_work_run`: Running deferred work. * `cleanup_mnt`: Cleaning up mount structures. * `deactivate_locked_super`: Deactivating the superblock. * `cifs_kill_sb`: CIFS-specific superblock kill function. * `kill_anon_super`: Generic anon superblock kill. * `generic_shutdown_super`: Generic superblock shutdown. * `shrink_dcache_for_umount`: Shrinking dcache for unmount. * `d_walk`: Walking the dentry tree. * `umount_check`: The function where the crash occurred. 4. **Determine the Root Cause**: * The crash is in `umount_check` while walking the dcache. * The `CR2` value (`0000556de4a6f808`) is a non-zero, non-NULL address. This suggests the kernel tried to dereference a pointer that was either invalid, freed, or corrupted. * Given the context of CIFS unmounting, this is likely a **use-after-free** or **race condition** in the CIFS driver or the VFS layer. The dentry cache might have been corrupted or freed while the kernel was still trying to walk it. * The `RAX: 0` suggests that a pointer that was expected to be valid was NULL or zero, or the result of a failed operation was used.
Conclusion: The kernel crashed during the unmount of a CIFS filesystem. The crash occurred in the `umount_check` function while walking the dentry cache (`d_walk`). The faulting address (`CR2`) indicates a memory access violation, likely due to a use-after-free or corrupted pointer in the dcache or CIFS driver. This is a serious bug in the kernel's V
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