Linux Kernel up to 6.2.6 fs/ext4/file.c i_disksize initialization

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.2.6. It has been declared as problematic. The impacted element is the function i_disksize of the file fs/ext4/file.c. Such manipulation leads to initialization. This vulnerability is uniquely identified as CVE-2023-53101. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.2.6 and classified as problematic. Affected by this issue is the function i_disksize of the file fs/ext4/file.c. The manipulation with an unknown input leads to a initialization vulnerability. Using CWE to declare the problem leads to CWE-665. The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used. The impact remains unknown. CVE summarizes:

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 advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2023-53101 since 05/02/2025. The exploitation is known to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 240448 (Amazon Linux 2 : kernel (ALAS-2025-2892)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.14.310, 4.19.278, 5.4.237, 5.10.175, 5.15.103, 6.1.20 or 6.2.7 eliminates this vulnerability. Applying the patch d6c1447e483c05dbcfb3ff77ac04237a82070b8c/59eee0cdf8c036f554add97a4da7c06d7a9ff34a/0d8a6c9a6415999fee1259ccf1796480c026b7d6/3f00c476da8fe7c4c34ea16abb55d74127120413/01a821aacc64d4b05dafd239dbc9b7856686002f/9cb27b1e76f0cc886ac09055bc41c0ab3f205167/9e9a4cc5486356158554f6ad73027d8635a48b34/f5361da1e60d54ec81346aee8e3d8baf1be0b762 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (240448). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.14.309
• 4.19.277
• 5.4.236
• 5.10.174
• 5.15.102
• 6.1.0
• 6.1.1
• 6.1.2
• 6.1.3
• 6.1.4
• 6.1.5
• 6.1.6
• 6.1.7
• 6.1.8
• 6.1.9
• 6.1.10
• 6.1.11
• 6.1.12
• 6.1.13
• 6.1.14
• 6.1.15
• 6.1.16
• 6.1.17
• 6.1.18
• 6.1.19
• 6.2.0
• 6.2.1
• 6.2.2
• 6.2.3
• 6.2.4
• 6.2.5
• 6.2.6

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

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