linux-cve-announce - CVE-2023-53101: ext4: zero i_disksize when initializing the bootloader inode

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Message-ID: <2025050224-CVE-2023-53101-3002@gregkh>
Date: Fri,  2 May 2025 17:56:06 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53101: ext4: zero i_disksize when initializing the bootloader inode

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

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

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

ext4: zero i_disksize when initializing the bootloader inode

If the boot loader inode has never been used before, the
EXT4_IOC_SWAP_BOOT inode will initialize it, including setting the
i_size to 0.  However, if the "never before used" boot loader has a
non-zero i_size, then i_disksize will be non-zero, and the
inconsistency between i_size and i_disksize can trigger a kernel
warning:

 WARNING: CPU: 0 PID: 2580 at fs/ext4/file.c:319
 CPU: 0 PID: 2580 Comm: bb Not tainted 6.3.0-rc1-00004-g703695902cfa
 RIP: 0010:ext4_file_write_iter+0xbc7/0xd10
 Call Trace:
  vfs_write+0x3b1/0x5c0
  ksys_write+0x77/0x160
  __x64_sys_write+0x22/0x30
  do_syscall_64+0x39/0x80

Reproducer:
 1. create corrupted image and mount it:
       mke2fs -t ext4 /tmp/foo.img 200
       debugfs -wR "sif <5> size 25700" /tmp/foo.img
       mount -t ext4 /tmp/foo.img /mnt
       cd /mnt
       echo 123 > file
 2. Run the reproducer program:
       posix_memalign(&buf, 1024, 1024)
       fd = open("file", O_RDWR | O_DIRECT);
       ioctl(fd, EXT4_IOC_SWAP_BOOT);
       write(fd, buf, 1024);

Fix this by setting i_disksize as well as i_size to zero when
initiaizing the boot loader inode.

The Linux kernel CVE team has assigned CVE-2023-53101 to this issue.


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

	Fixed in 4.14.310 with commit d6c1447e483c05dbcfb3ff77ac04237a82070b8c
	Fixed in 4.19.278 with commit 59eee0cdf8c036f554add97a4da7c06d7a9ff34a
	Fixed in 5.4.237 with commit 0d8a6c9a6415999fee1259ccf1796480c026b7d6
	Fixed in 5.10.175 with commit 3f00c476da8fe7c4c34ea16abb55d74127120413
	Fixed in 5.15.103 with commit 01a821aacc64d4b05dafd239dbc9b7856686002f
	Fixed in 6.1.20 with commit 9cb27b1e76f0cc886ac09055bc41c0ab3f205167
	Fixed in 6.2.7 with commit 9e9a4cc5486356158554f6ad73027d8635a48b34
	Fixed in 6.3 with commit f5361da1e60d54ec81346aee8e3d8baf1be0b762

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-2023-53101
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/ioctl.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/d6c1447e483c05dbcfb3ff77ac04237a82070b8c
	https://git.kernel.org/stable/c/59eee0cdf8c036f554add97a4da7c06d7a9ff34a
	https://git.kernel.org/stable/c/0d8a6c9a6415999fee1259ccf1796480c026b7d6
	https://git.kernel.org/stable/c/3f00c476da8fe7c4c34ea16abb55d74127120413
	https://git.kernel.org/stable/c/01a821aacc64d4b05dafd239dbc9b7856686002f
	https://git.kernel.org/stable/c/9cb27b1e76f0cc886ac09055bc41c0ab3f205167
	https://git.kernel.org/stable/c/9e9a4cc5486356158554f6ad73027d8635a48b34
	https://git.kernel.org/stable/c/f5361da1e60d54ec81346aee8e3d8baf1be0b762