CVE-2023-53800 in Linux
Summary
by MITRE • 12/09/2025
In the Linux kernel, the following vulnerability has been resolved:
ubi: Fix use-after-free when volume resizing failed
There is an use-after-free problem reported by KASAN: ================================================================== BUG: KASAN: use-after-free in ubi_eba_copy_table+0x11f/0x1c0 [ubi]
Read of size 8 at addr ffff888101eec008 by task ubirsvol/4735
CPU: 2 PID: 4735 Comm: ubirsvol Not tainted 6.1.0-rc1-00003-g84fa3304a7fc-dirty #14 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x34/0x44 print_report+0x171/0x472 kasan_report+0xad/0x130 ubi_eba_copy_table+0x11f/0x1c0 [ubi]
ubi_resize_volume+0x4f9/0xbc0 [ubi]
ubi_cdev_ioctl+0x701/0x1850 [ubi]
__x64_sys_ioctl+0x11d/0x170 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 </TASK>
When ubi_change_vtbl_record() returns an error in ubi_resize_volume(), "new_eba_tbl" will be freed on error handing path, but it is holded by "vol->eba_tbl" in ubi_eba_replace_table(). It means that the liftcycle of "vol->eba_tbl" and "vol" are different, so when resizing volume in next time, it causing an use-after-free fault.
Fix it by not freeing "new_eba_tbl" after it replaced in ubi_eba_replace_table(), while will be freed in next volume resizing.
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Analysis
by VulDB Data Team • 03/29/2026
The vulnerability CVE-2023-53800 represents a critical use-after-free condition within the Linux Unified Block Interface (UBI) subsystem, specifically affecting the ubi_resize_volume function. This flaw occurs during volume resizing operations when the system encounters an error during the ubi_change_vtbl_record() call. The underlying issue stems from improper memory management where the new EBA (Erasure Block Allocator) table structure is prematurely freed during error handling, while simultaneously being referenced by the volume's EBA table pointer. The kernel's KASAN (Kernel Address Sanitizer) detection mechanism identified this problem through a read operation of size 8 at address ffff888101eec008, originating from the ubi_eba_copy_table function. This memory access pattern indicates that the system attempts to read from memory that has already been deallocated, creating a potential exploitation vector for malicious actors.
The technical root cause of this vulnerability can be traced to a mismatch in object lifecycle management between the volume structure and its associated EBA table. When ubi_resize_volume() encounters an error, it follows an error handling path that frees the "new_eba_tbl" memory allocation, but this table has already been assigned to "vol->eba_tbl" through the ubi_eba_replace_table() function. This creates a scenario where the volume structure maintains a reference to memory that has been freed, leading to the use-after-free condition. The flaw demonstrates poor resource management practices where the same memory location is managed by two different lifecycle mechanisms, violating fundamental principles of memory safety in kernel space operations. This issue is particularly concerning as it occurs within the UBI subsystem which provides block-level access to raw flash devices, making it a critical component for embedded systems and storage solutions.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling privilege escalation and system instability. Attackers could exploit this condition to execute arbitrary code with kernel privileges, leveraging the use-after-free to manipulate memory layout and potentially gain full system control. The vulnerability affects systems running Linux kernel versions where UBI is enabled, particularly those utilizing flash-based storage solutions such as NAND flash memory devices. The specific call trace shows that the issue manifests during ioctl system calls, indicating that user-space applications interacting with UBI devices through device files could trigger this vulnerability. This makes the flaw particularly dangerous in embedded environments where such devices are commonly deployed, including IoT devices, routers, and embedded storage systems.
The fix implemented addresses the core memory management issue by modifying the ubi_eba_replace_table() function to prevent premature freeing of the EBA table structure after it has been successfully replaced. Instead of freeing "new_eba_tbl" immediately upon error conditions, the solution ensures that memory cleanup occurs during subsequent volume resizing operations when the table is no longer needed. This approach aligns with the established CWE-416 principle of "Use After Free" which emphasizes proper memory lifecycle management and prevents access to deallocated memory regions. The mitigation strategy follows ATT&CK technique T1068 by addressing privilege escalation vectors through kernel memory corruption, ensuring that the system maintains memory integrity during dynamic resource allocation and deallocation. This fix demonstrates the importance of careful resource management in kernel space, where improper handling of object lifecycles can lead to severe security implications that affect system stability and security posture across embedded and enterprise environments.