CVE-2025-38716 in Linux
Summary
by MITRE • 09/04/2025
In the Linux kernel, the following vulnerability has been resolved:
hfs: fix general protection fault in hfs_find_init()
The hfs_find_init() method can trigger the crash if tree pointer is NULL:
[ 45.746290][ T9787] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] SMP KAI
[ 45.747287][ T9787] KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
[ 45.748716][ T9787] CPU: 2 UID: 0 PID: 9787 Comm: repro Not tainted 6.16.0-rc3 #10 PREEMPT(full)
[ 45.750250][ T9787] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 45.751983][ T9787] RIP: 0010:hfs_find_init+0x86/0x230
[ 45.752834][ T9787] Code: c1 ea 03 80 3c 02 00 0f 85 9a 01 00 00 4c 8d 6b 40 48 c7 45 18 00 00 00 00 48 b8 00 00 00 00 00 fc
[ 45.755574][ T9787] RSP: 0018:ffffc90015157668 EFLAGS: 00010202
[ 45.756432][ T9787] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff819a4d09
[ 45.757457][ T9787] RDX: 0000000000000008 RSI: ffffffff819acd3a RDI: ffffc900151576e8
[ 45.758282][ T9787] RBP: ffffc900151576d0 R08: 0000000000000005 R09: 0000000000000000
[ 45.758943][ T9787] R10: 0000000080000000 R11: 0000000000000001 R12: 0000000000000004
[ 45.759619][ T9787] R13: 0000000000000040 R14: ffff88802c50814a R15: 0000000000000000
[ 45.760293][ T9787] FS: 00007ffb72734540(0000) GS:ffff8880cec64000(0000) knlGS:0000000000000000
[ 45.761050][ T9787] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 45.761606][ T9787] CR2: 00007f9bd8225000 CR3: 000000010979a000 CR4: 00000000000006f0
[ 45.762286][ T9787] Call Trace:
[ 45.762570][ T9787] <TASK>
[ 45.762824][ T9787] hfs_ext_read_extent+0x190/0x9d0
[ 45.763269][ T9787] ? submit_bio_noacct_nocheck+0x2dd/0xce0
[ 45.763766][ T9787] ? __pfx_hfs_ext_read_extent+0x10/0x10
[ 45.764250][ T9787] hfs_get_block+0x55f/0x830
[ 45.764646][ T9787] block_read_full_folio+0x36d/0x850
[ 45.765105][ T9787] ? __pfx_hfs_get_block+0x10/0x10
[ 45.765541][ T9787] ? const_folio_flags+0x5b/0x100
[ 45.765972][ T9787] ? __pfx_hfs_read_folio+0x10/0x10
[ 45.766415][ T9787] filemap_read_folio+0xbe/0x290
[ 45.766840][ T9787] ? __pfx_filemap_read_folio+0x10/0x10
[ 45.767325][ T9787] ? __filemap_get_folio+0x32b/0xbf0
[ 45.767780][ T9787] do_read_cache_folio+0x263/0x5c0
[ 45.768223][ T9787] ? __pfx_hfs_read_folio+0x10/0x10
[ 45.768666][ T9787] read_cache_page+0x5b/0x160
[ 45.769070][ T9787] hfs_btree_open+0x491/0x1740
[ 45.769481][ T9787] hfs_mdb_get+0x15e2/0x1fb0
[ 45.769877][ T9787] ? __pfx_hfs_mdb_get+0x10/0x10
[ 45.770316][ T9787] ? find_held_lock+0x2b/0x80
[ 45.770731][ T9787] ? lockdep_init_map_type+0x5c/0x280
[ 45.771200][ T9787] ? lockdep_init_map_type+0x5c/0x280
[ 45.771674][ T9787] hfs_fill_super+0x38e/0x720
[ 45.772092][ T9787] ? __pfx_hfs_fill_super+0x10/0x10
[ 45.772549][ T9787] ? snprintf+0xbe/0x100
[ 45.772931][ T9787] ? __pfx_snprintf+0x10/0x10
[ 45.773350][ T9787] ? do_raw_spin_lock+0x129/0x2b0
[ 45.773796][ T9787] ? find_held_lock+0x2b/0x80
[ 45.774215][ T9787] ? set_blocksize+0x40a/0x510
[ 45.774636][ T9787] ? sb_set_blocksize+0x176/0x1d0
[ 45.775087][ T9787] ? setup_bdev_super+0x369/0x730
[ 45.775533][ T9787] get_tree_bdev_flags+0x384/0x620
[ 45.775985][ T9787] ? __pfx_hfs_fill_super+0x10/0x10
[ 45.776453][ T9787] ? __pfx_get_tree_bdev_flags+0x10/0x10
[ 45.776950][ T9787] ? bpf_lsm_capable+0x9/0x10
[ 45.777365][ T9787] ? security_capable+0x80/0x260
[ 45.777803][ T9787] vfs_get_tree+0x8e/0x340
[ 45.778203][ T9787] path_mount+0x13de/0x2010
[ 45.778604][ T9787] ? kmem_cache_free+0x2b0/0x4c0
[ 45.779052][ T9787] ? __pfx_path_mount+0x10/0x10
[ 45.779480][ T9787] ? getname_flags.part.0+0x1c5/0x550
[ 45.779954][ T9787] ? putname+0x154/0x1a0
[ 45.780335][ T9787] __x64_sys_mount+0x27b/0x300
[ 45.780758][ T9787] ? __pfx___x64_sys_mount+0x10/0x10
[ 45.781232][ T9787]
---truncated---
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Analysis
by VulDB Data Team • 02/10/2026
The vulnerability CVE-2025-38716 resides within the Linux kernel's HFS (Hierarchical File System) implementation, specifically within the hfs_find_init() function. This flaw manifests as a general protection fault occurring when the tree pointer is NULL, leading to a kernel oops and system crash. The issue stems from an unchecked null pointer dereference during file system operations, which can be triggered during mount or file access procedures. The error trace shows the fault occurring at RIP: 0010:hfs_find_init+0x86/0x230, indicating that the kernel attempted to access memory at an invalid address, resulting in a KASAN null-ptr-deref error. This vulnerability is particularly concerning as it can be exploited to cause a denial of service or potentially escalate privileges depending on the execution context, making it a critical target for exploitation.
The technical flaw in this vulnerability is rooted in improper validation of input parameters within the hfs_find_init() function. The function fails to check whether the tree pointer is NULL before attempting to dereference it, leading to a kernel panic when the system attempts to access memory that has not been properly initialized. According to CWE-476, this vulnerability maps directly to a null pointer dereference, where a pointer that is expected to point to a valid memory location is NULL. The system crash occurs during a call chain that begins with hfs_fill_super, which is responsible for initializing the file system superblock, and proceeds through hfs_mdb_get and hfs_btree_open before reaching the vulnerable hfs_find_init function. The call trace demonstrates a complex interaction between the file system layer and block device handling, suggesting that the vulnerability could be triggered through various paths including mount operations, file reads, or metadata access.
The operational impact of CVE-2025-38716 extends beyond simple system crashes, presenting a potential vector for persistent denial of service attacks against systems relying on HFS file systems. When exploited, the vulnerability can cause complete system instability, requiring manual reboot or recovery procedures. The vulnerability is particularly relevant in environments where legacy HFS file systems are still in use, such as older macOS systems or embedded devices that maintain compatibility with HFS formats. From an ATT&CK perspective, this vulnerability aligns with T1499.004 (Endpoint Denial of Service) and could be leveraged in combination with other techniques to disrupt service availability. The vulnerability affects systems running kernel versions that include the affected HFS implementation, making it a target for exploitation in environments where kernel updates are delayed or not applied promptly. The specific nature of the crash, occurring in a file system driver, suggests that exploitation could potentially be achieved through crafted file system images or by manipulating file system metadata.
Mitigation strategies for CVE-2025-38716 should prioritize immediate kernel updates from the Linux kernel maintainers, as the fix has already been resolved in upstream versions. System administrators should ensure that all affected systems are updated to kernel versions containing the patched hfs_find_init() function, which implements proper NULL pointer validation. Additionally, monitoring for kernel oops messages and system crashes related to HFS operations should be implemented to detect potential exploitation attempts. The vulnerability can also be mitigated through filesystem access controls and limiting user privileges when mounting HFS file systems. Organizations should consider disabling HFS support entirely if the file system is not required, reducing the attack surface. Security teams should also implement proper intrusion detection systems to monitor for unusual file system access patterns that might indicate exploitation attempts. For systems where immediate updates are not feasible, implementing network segmentation and restricting access to systems that mount HFS volumes can provide additional defense in depth. The vulnerability's classification as a kernel-level flaw means that mitigations must be applied at the operating system level, as application-level protections are insufficient to address the underlying memory corruption issue.