CVE-2024-53221 in Linux
Summary
by MITRE • 12/27/2024
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix null-ptr-deref in f2fs_submit_page_bio()
There's issue as follows when concurrently installing the f2fs.ko module and mounting the f2fs file system: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
RIP: 0010:__bio_alloc+0x2fb/0x6c0 [f2fs]
Call Trace: <TASK> f2fs_submit_page_bio+0x126/0x8b0 [f2fs]
__get_meta_page+0x1d4/0x920 [f2fs]
get_checkpoint_version.constprop.0+0x2b/0x3c0 [f2fs]
validate_checkpoint+0xac/0x290 [f2fs]
f2fs_get_valid_checkpoint+0x207/0x950 [f2fs]
f2fs_fill_super+0x1007/0x39b0 [f2fs]
mount_bdev+0x183/0x250 legacy_get_tree+0xf4/0x1e0 vfs_get_tree+0x88/0x340 do_new_mount+0x283/0x5e0 path_mount+0x2b2/0x15b0 __x64_sys_mount+0x1fe/0x270 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e
Above issue happens as the biset of the f2fs file system is not initialized before register "f2fs_fs_type". To address above issue just register "f2fs_fs_type" at the last in init_f2fs_fs(). Ensure that all f2fs file system resources are initialized.
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Analysis
by VulDB Data Team • 06/01/2026
The vulnerability CVE-2024-53221 represents a critical null pointer dereference flaw in the Linux kernel's f2fs file system implementation that occurs during concurrent module loading and file system mounting operations. This issue manifests as a kernel address sanitizer (KASAN) error indicating a null pointer dereference within the range 0x0000000000000020-0x0000000000000027, specifically during execution of the __bio_alloc function. The root cause stems from improper initialization sequencing within the f2fs file system driver where the f2fs_fs_type registration occurs before all necessary file system resources have been properly initialized, creating a race condition that can lead to system instability or potential privilege escalation.
The technical flaw exists in the initialization sequence of the f2fs file system driver within the init_f2fs_fs() function, where the registration of f2fs_fs_type happens prematurely before the bitmap initialization process completes. This creates a scenario where concurrent operations attempting to load the f2fs.ko module while simultaneously mounting an f2fs file system can trigger the null pointer dereference. The call trace demonstrates the execution path leading to the vulnerability through multiple kernel functions including f2fs_submit_page_bio, __get_meta_page, validate_checkpoint, and f2fs_fill_super, ultimately failing at the mount_bdev function. This vulnerability aligns with CWE-476 which describes NULL Pointer Dereference, and represents a classic initialization race condition that can be exploited through improper resource management.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable privilege escalation attacks and denial of service conditions in environments where f2fs file systems are actively used. Attackers could exploit this flaw by carefully orchestrating concurrent module loading and mounting operations to trigger the null pointer dereference, potentially leading to kernel panic or system compromise. The vulnerability is particularly concerning in embedded systems or cloud environments where f2fs file systems are commonly deployed, as it can be leveraged to disrupt critical operations. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Exploitation for Privilege Escalation) and T1499 (Endpoint Denial of Service) through the potential for privilege escalation and system disruption.
The fix implemented addresses the core initialization ordering issue by ensuring that f2fs_fs_type registration occurs at the final stage of the init_f2fs_fs() function, guaranteeing that all required file system resources are properly initialized before the registration process begins. This solution follows the principle of proper resource initialization and dependency management, preventing the race condition that enabled the vulnerability. The mitigation strategy requires kernel updates that implement this corrected initialization sequence, with system administrators needing to apply the patched kernel versions to prevent exploitation. Organizations should prioritize this update, particularly in environments where f2fs file systems are actively used, as the vulnerability can be reliably exploited through concurrent module loading and mounting operations. The fix demonstrates proper kernel development practices for managing initialization dependencies and resource allocation, aligning with established security best practices for kernel module development and system stability.