linux-cve-announce - CVE-2025-68261: ext4: add i_data_sem protection in ext4_destroy_inline_data

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Message-ID: <2025121614-CVE-2025-68261-4e23@gregkh>
Date: Tue, 16 Dec 2025 15:45:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68261: ext4: add i_data_sem protection in ext4_destroy_inline_data_nolock()

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

ext4: add i_data_sem protection in ext4_destroy_inline_data_nolock()

Fix a race between inline data destruction and block mapping.

The function ext4_destroy_inline_data_nolock() changes the inode data
layout by clearing EXT4_INODE_INLINE_DATA and setting EXT4_INODE_EXTENTS.
At the same time, another thread may execute ext4_map_blocks(), which
tests EXT4_INODE_EXTENTS to decide whether to call ext4_ext_map_blocks()
or ext4_ind_map_blocks().

Without i_data_sem protection, ext4_ind_map_blocks() may receive inode
with EXT4_INODE_EXTENTS flag and triggering assert.

kernel BUG at fs/ext4/indirect.c:546!
EXT4-fs (loop2): unmounting filesystem.
invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:ext4_ind_map_blocks.cold+0x2b/0x5a fs/ext4/indirect.c:546

Call Trace:
 <TASK>
 ext4_map_blocks+0xb9b/0x16f0 fs/ext4/inode.c:681
 _ext4_get_block+0x242/0x590 fs/ext4/inode.c:822
 ext4_block_write_begin+0x48b/0x12c0 fs/ext4/inode.c:1124
 ext4_write_begin+0x598/0xef0 fs/ext4/inode.c:1255
 ext4_da_write_begin+0x21e/0x9c0 fs/ext4/inode.c:3000
 generic_perform_write+0x259/0x5d0 mm/filemap.c:3846
 ext4_buffered_write_iter+0x15b/0x470 fs/ext4/file.c:285
 ext4_file_write_iter+0x8e0/0x17f0 fs/ext4/file.c:679
 call_write_iter include/linux/fs.h:2271 [inline]
 do_iter_readv_writev+0x212/0x3c0 fs/read_write.c:735
 do_iter_write+0x186/0x710 fs/read_write.c:861
 vfs_iter_write+0x70/0xa0 fs/read_write.c:902
 iter_file_splice_write+0x73b/0xc90 fs/splice.c:685
 do_splice_from fs/splice.c:763 [inline]
 direct_splice_actor+0x10f/0x170 fs/splice.c:950
 splice_direct_to_actor+0x33a/0xa10 fs/splice.c:896
 do_splice_direct+0x1a9/0x280 fs/splice.c:1002
 do_sendfile+0xb13/0x12c0 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x1cf/0x210 fs/read_write.c:1309
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

The Linux kernel CVE team has assigned CVE-2025-68261 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.11 with commit c755e251357a0cee0679081f08c3f4ba797a8009 and fixed in 6.12.62 with commit 22a76b0861ae61a299c8e126c1aca8c4fda820fd
	Issue introduced in 4.11 with commit c755e251357a0cee0679081f08c3f4ba797a8009 and fixed in 6.17.12 with commit ba8aeff294ac7ff6dfe293663d815c54c5ee218c
	Issue introduced in 4.11 with commit c755e251357a0cee0679081f08c3f4ba797a8009 and fixed in 6.18.1 with commit 5cad18e527ba8a9ca5463cc170073eeb5a4826f4
	Issue introduced in 4.11 with commit c755e251357a0cee0679081f08c3f4ba797a8009 and fixed in 6.19-rc1 with commit 0cd8feea8777f8d9b9a862b89c688b049a5c8475
	Issue introduced in 3.16.44 with commit 3e96c3fdcfccb321a9e1623f78cc71b44593e965
	Issue introduced in 3.18.107 with commit 5781ac24bbd998ebb1ff30143bb06244d847af48
	Issue introduced in 4.4.129 with commit 9b06cce3ca4d60d442c39bfa7c058b71b1cee6c2
	Issue introduced in 4.9.14 with commit da1e40237f8f3516581b534c484c236a79ccfd14
	Issue introduced in 4.10.2 with commit 7cf6b709b6412afd1d93b2c4b37163c3602e3b95

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-2025-68261
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/inline.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/22a76b0861ae61a299c8e126c1aca8c4fda820fd
	https://git.kernel.org/stable/c/ba8aeff294ac7ff6dfe293663d815c54c5ee218c
	https://git.kernel.org/stable/c/5cad18e527ba8a9ca5463cc170073eeb5a4826f4
	https://git.kernel.org/stable/c/0cd8feea8777f8d9b9a862b89c688b049a5c8475