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Message-ID: <2025070425-CVE-2025-38221-f152@gregkh>
Date: Fri, 4 Jul 2025 15:37:50 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38221: ext4: fix out of bounds punch offset
From: Greg Kroah-Hartman <gregkh@...nel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix out of bounds punch offset
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.
The Linux kernel CVE team has assigned CVE-2025-38221 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.15 with commit 982bf37da09d078570650b691d9084f43805a5de and fixed in 6.15.4 with commit 28b62cb58fd014338f5004170f2e3a35bf0af238
Issue introduced in 6.15 with commit 982bf37da09d078570650b691d9084f43805a5de and fixed in 6.16-rc1 with commit b5e58bcd79625423487fa3ecba8e8411b5396327
Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.
Unaffected versions might change over time as fixes are backported to
older supported kernel versions. The official CVE entry at
https://cve.org/CVERecord/?id=CVE-2025-38221
will be updated if fixes are backported, please check that for the most
up to date information about this issue.
Affected files
==============
The file(s) affected by this issue are:
fs/ext4/inode.c
Mitigation
==========
The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes. Individual
changes are never tested alone, but rather are part of a larger kernel
release. Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all. If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
https://git.kernel.org/stable/c/28b62cb58fd014338f5004170f2e3a35bf0af238
https://git.kernel.org/stable/c/b5e58bcd79625423487fa3ecba8e8411b5396327
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