ext4: fix out of bounds punch offset

published 2025-07-04 16 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-20035

cvss: 7.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

Punching a hole with a start offset that exceeds max_end is not permitted and will result in a negative length in the truncate_inode_partial_folio() function while truncating the page cache, potentially leading to undesirable consequences.

A simple reproducer:

truncate -s 9895604649994 /mnt/foo xfs_io -c "pwrite 8796093022208 4096" /mnt/foo xfs_io -c "fpunch 8796093022213 25769803777" /mnt/foo

kernel BUG at include/linux/highmem.h:275! Oops: invalid opcode: 0000 [#1] SMP PTI CPU: 3 UID: 0 PID: 710 Comm: xfs_io Not tainted 6.15.0-rc3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:zero_user_segments.constprop.0+0xd7/0x110 RSP: 0018:ffffc90001cf3b38 EFLAGS: 00010287 RAX: 0000000000000005 RBX: ffffea0001485e40 RCX: 0000000000001000 RDX: 000000000040b000 RSI: 0000000000000005 RDI: 000000000040b000 RBP: 000000000040affb R08: ffff888000000000 R09: ffffea0000000000 R10: 0000000000000003 R11: 00000000fffc7fc5 R12: 0000000000000005 R13: 000000000040affb R14: ffffea0001485e40 R15: ffff888031cd3000 FS: 00007f4f63d0b780(0000) GS:ffff8880d337d000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000001ae0b038 CR3: 00000000536aa000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> truncate_inode_partial_folio+0x3dd/0x620 truncate_inode_pages_range+0x226/0x720 ? bdev_getblk+0x52/0x3e0 ? ext4_get_group_desc+0x78/0x150 ? crc32c_arch+0xfd/0x180 ? __ext4_get_inode_loc+0x18c/0x840 ? ext4_inode_csum+0x117/0x160 ? jbd2_journal_dirty_metadata+0x61/0x390 ? __ext4_handle_dirty_metadata+0xa0/0x2b0 ? kmem_cache_free+0x90/0x5a0 ? jbd2_journal_stop+0x1d5/0x550 ? __ext4_journal_stop+0x49/0x100 truncate_pagecache_range+0x50/0x80 ext4_truncate_page_cache_block_range+0x57/0x3a0 ext4_punch_hole+0x1fe/0x670 ext4_fallocate+0x792/0x17d0 ? __count_memcg_events+0x175/0x2a0 vfs_fallocate+0x121/0x560 ksys_fallocate+0x51/0xc0 __x64_sys_fallocate+0x24/0x40 x64_sys_call+0x18d2/0x4170 do_syscall_64+0xa7/0x220 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Fix this by filtering out cases where the punching start offset exceeds max_end.

Patch / fix

fixed in 1 links 3

Linux Linux 6.15.4, 6.16

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38221 updated 2026-11-06

kernel: ext4: fix out of bounds punch offset

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-125 Out-of-bounds Read

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-38221
NVD CVE-2025-38221

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary