CVE-2025-38442 block: reject bs > ps block devices when THP is disabled
A null pointer dereference in the Linux kernel block layer causes a system panic during boot when Transparent Huge Pages are disabled and a block device with a large logical block size is present.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38442?
CVE-2025-38442 is a medium-severity vulnerability in Linux kernel, published on 25 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
block: reject bs > ps block devices when THP is disabled
If THP is disabled and when a block device with logical block size > page size is present, the following null ptr deref panic happens during boot:
[ [13.2 mK AOSAN: null-ptr-deref in range [0x0000000000000000-0x0000000000K0 0 0[07] [ 13.017749] RIP: 0010:create_empty_buffers+0x3b/0x380 <snip> [ 13.025448] Call Trace: [ 13.025692] <TASK> [ 13.025895] block_read_full_folio+0x610/0x780 [ 13.026379] ? __pfx_blkdev_get_block+0x10/0x10 [ 13.027008] ? __folio_batch_add_and_move+0x1fa/0x2b0 [ 13.027548] ? __pfx_blkdev_read_folio+0x10/0x10 [ 13.028080] filemap_read_folio+0x9b/0x200 [ 13.028526] ? __pfx_filemap_read_folio+0x10/0x10 [ 13.029030] ? __filemap_get_folio+0x43/0x620 [ 13.029497] do_read_cache_folio+0x155/0x3b0 [ 13.029962] ? __pfx_blkdev_read_folio+0x10/0x10 [ 13.030381] read_part_sector+0xb7/0x2a0 [ 13.030805] read_lba+0x174/0x2c0 <snip> [ 13.045348] nvme_scan_ns+0x684/0x850 [nvme_core] [ 13.045858] ? __pfx_nvme_scan_ns+0x10/0x10 [nvme_core] [ 13.046414] ? _raw_spin_unlock+0x15/0x40 [ 13.046843] ? __switch_to+0x523/0x10a0 [ 13.047253] ? kvm_clock_get_cycles+0x14/0x30 [ 13.047742] ? __pfx_nvme_scan_ns_async+0x10/0x10 [nvme_core] [ 13.048353] async_run_entry_fn+0x96/0x4f0 [ 13.048787] process_one_work+0x667/0x10a0 [ 13.049219] worker_thread+0x63c/0xf60
As large folio support depends on THP, only allow bs > ps block devices if THP is enabled.
Weakness: CWE-476
Which versions are affected by CVE-2025-38442?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-38442?
Apply the vendor's patch.
Is CVE-2025-38442 being exploited?
There is no known exploitation of CVE-2025-38442 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-38442, GHSA-p7jf-wq44-hqq3, UBUNTU-CVE-2025-38442.