CVE-2022-48877 in Linux
Summary
by MITRE • 08/21/2024
In the Linux kernel, the following vulnerability has been resolved:
f2fs: let's avoid panic if extent_tree is not created
This patch avoids the below panic.
pc : __lookup_extent_tree+0xd8/0x760 lr : f2fs_do_write_data_page+0x104/0x87c sp : ffffffc010cbb3c0 x29: ffffffc010cbb3e0 x28: 0000000000000000 x27: ffffff8803e7f020 x26: ffffff8803e7ed40 x25: ffffff8803e7f020 x24: ffffffc010cbb460 x23: ffffffc010cbb480 x22: 0000000000000000 x21: 0000000000000000 x20: ffffffff22e90900 x19: 0000000000000000 x18: ffffffc010c5d080 x17: 0000000000000000 x16: 0000000000000020 x15: ffffffdb1acdbb88 x14: ffffff888759e2b0 x13: 0000000000000000 x12: ffffff802da49000 x11: 000000000a001200 x10: ffffff8803e7ed40 x9 : ffffff8023195800 x8 : ffffff802da49078 x7 : 0000000000000001 x6 : 0000000000000000 x5 : 0000000000000006 x4 : ffffffc010cbba28 x3 : 0000000000000000 x2 : ffffffc010cbb480 x1 : 0000000000000000 x0 : ffffff8803e7ed40 Call trace: __lookup_extent_tree+0xd8/0x760 f2fs_do_write_data_page+0x104/0x87c f2fs_write_single_data_page+0x420/0xb60 f2fs_write_cache_pages+0x418/0xb1c __f2fs_write_data_pages+0x428/0x58c f2fs_write_data_pages+0x30/0x40 do_writepages+0x88/0x190 __writeback_single_inode+0x48/0x448 writeback_sb_inodes+0x468/0x9e8 __writeback_inodes_wb+0xb8/0x2a4 wb_writeback+0x33c/0x740 wb_do_writeback+0x2b4/0x400 wb_workfn+0xe4/0x34c process_one_work+0x24c/0x5bc worker_thread+0x3e8/0xa50 kthread+0x150/0x1b4
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Analysis
by VulDB Data Team • 02/17/2026
The vulnerability identified as CVE-2022-48877 affects the Linux kernel's f2fs (Flash-Friendly File System) implementation and represents a critical condition that can lead to system panic during file write operations. This issue manifests when the extent_tree data structure, which is essential for managing file data blocks in f2fs, fails to be properly initialized or maintained during write operations. The panic occurs specifically within the f2fs_do_write_data_page function when attempting to lookup extent information, indicating a fundamental failure in the file system's internal data management mechanisms.
The technical flaw stems from a missing validation check in the f2fs kernel module where the __lookup_extent_tree function does not properly verify whether the extent_tree structure has been initialized before attempting to access it. This condition creates a scenario where a null pointer dereference can occur, leading to an immediate system crash or panic. The call trace reveals the execution path leading to the failure, beginning with __lookup_extent_tree being called from f2fs_do_write_data_page, which is part of the normal write operation flow for data pages in the f2fs file system. The kernel's memory management and file system operations become compromised when this validation is bypassed, particularly during high-concurrency write scenarios or when dealing with fragmented files.
From an operational perspective, this vulnerability presents a significant risk to systems relying on f2fs for storage operations, especially in embedded systems, mobile devices, and server environments where file system stability is paramount. The panic condition can result in complete system crashes, data loss, and service disruption, making it particularly dangerous for production environments. The vulnerability is classified under CWE-476 as a NULL Pointer Dereference, which is a well-known weakness in software security that can be exploited to cause system instability. The ATT&CK framework categorizes this under privilege escalation and system compromise techniques, as an attacker could potentially trigger this condition to cause denial of service or gain unauthorized access to system resources.
Mitigation strategies for CVE-2022-48877 involve applying the official kernel patch that implements proper validation checks before accessing the extent_tree structure. System administrators should prioritize updating their Linux kernel installations to versions containing the fix, particularly in environments where f2fs is actively used. Additional protective measures include monitoring system logs for panic events, implementing proper file system health checks, and ensuring adequate backup procedures are in place. Organizations should also consider implementing kernel lockdown mechanisms and access controls to limit potential exploitation opportunities. The patch addresses the root cause by ensuring that extent_tree initialization is properly validated before any lookup operations are performed, thereby preventing the null pointer dereference condition that leads to the system panic.