CVE-2023-53537 in Linux
Summary
by MITRE • 10/04/2025
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid use-after-free for cached IPU bio
xfstest generic/019 reports a bug:
kernel BUG at mm/filemap.c:1619! RIP: 0010:folio_end_writeback+0x8a/0x90 Call Trace: end_page_writeback+0x1c/0x60 f2fs_write_end_io+0x199/0x420 bio_endio+0x104/0x180 submit_bio_noacct+0xa5/0x510 submit_bio+0x48/0x80 f2fs_submit_write_bio+0x35/0x300 f2fs_submit_merged_ipu_write+0x2a0/0x2b0 f2fs_write_single_data_page+0x838/0x8b0 f2fs_write_cache_pages+0x379/0xa30 f2fs_write_data_pages+0x30c/0x340 do_writepages+0xd8/0x1b0 __writeback_single_inode+0x44/0x370 writeback_sb_inodes+0x233/0x4d0 __writeback_inodes_wb+0x56/0xf0 wb_writeback+0x1dd/0x2d0 wb_workfn+0x367/0x4a0 process_one_work+0x21d/0x430 worker_thread+0x4e/0x3c0 kthread+0x103/0x130 ret_from_fork+0x2c/0x50
The root cause is: after cp_error is set, f2fs_submit_merged_ipu_write() in f2fs_write_single_data_page() tries to flush IPU bio in cache, however f2fs_submit_merged_ipu_write() missed to check validity of @bio parameter, result in submitting random cached bio which belong to other IO context, then it will cause use-after-free issue, fix it by adding additional validity check.
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Analysis
by VulDB Data Team • 03/01/2026
The vulnerability CVE-2023-53537 represents a critical use-after-free condition in the Linux kernel's f2fs filesystem implementation that arises during I/O operations involving cached IPU (In-Place Update) bio structures. This issue manifests when the kernel attempts to handle write operations on f2fs filesystems, specifically during the cleanup phase of I/O completion. The bug is particularly concerning because it occurs in the kernel's memory management subsystem, where improper handling of I/O bio structures can lead to system instability and potential privilege escalation. The vulnerability was identified through xfstest generic/019 which revealed a kernel BUG at mm/filemap.c:1619, indicating a critical failure in the folio_end_writeback function. The call trace demonstrates a clear path through the f2fs I/O subsystem where the kernel attempts to submit bio operations that have already been freed or are otherwise invalid.
The technical root cause stems from a missing validation check in the f2fs_submit_merged_ipu_write function within the f2fs_write_single_data_page context. When a checkpoint error occurs, the system attempts to flush cached IPU bio structures, but the function fails to validate the bio parameter before proceeding with submission. This oversight allows the kernel to submit bio structures that belong to different I/O contexts or have already been freed, creating a scenario where memory is accessed after it has been released. The flaw directly relates to CWE-416, which describes the use of freed memory condition, and demonstrates how improper resource management in kernel space can lead to severe system vulnerabilities. The specific failure occurs at the bio_endio function in the I/O submission chain, where random cached bio structures are submitted, causing undefined behavior that can result in kernel panics or memory corruption.
The operational impact of this vulnerability extends beyond simple system instability to potentially enable privilege escalation and denial of service conditions. When the kernel submits invalid bio structures, it can cause memory corruption that may be exploited by malicious actors to gain elevated privileges or to crash the system entirely. The vulnerability affects systems running Linux kernels with f2fs filesystem support, particularly those handling heavy I/O workloads where checkpoint operations and IPU bio caching are common. Attackers could potentially trigger this condition through specific write operations that cause checkpoint errors, leading to a system crash or more severe consequences depending on the execution context. The vulnerability's impact is amplified by its location in the kernel's core memory management functions, which are fundamental to system operation and security. This issue aligns with ATT&CK technique T1068, which covers the use of privilege escalation techniques through kernel vulnerabilities, and T1499, which covers the exploitation of system resource exhaustion or corruption.
Mitigation strategies for CVE-2023-53537 require immediate patch application from kernel vendors, as the vulnerability exists in the core kernel I/O subsystem. System administrators should prioritize updating their Linux kernels to versions that include the fix for this specific use-after-free condition. The patch implements additional validation checks in the f2fs_submit_merged_ipu_write function to ensure that bio structures are valid before submission, preventing the use of freed or invalid memory references. Organizations should also consider implementing monitoring for unusual I/O patterns that might indicate exploitation attempts, particularly around checkpoint operations and I/O completion handling. The fix addresses the underlying resource management issue by ensuring proper validation of I/O bio structures before they are submitted to the kernel's I/O subsystem, thereby preventing the use-after-free condition that leads to memory corruption. Additionally, system hardening measures including kernel lockdown features and secure boot configurations can provide additional protection layers against exploitation attempts targeting this vulnerability.