CVE-2025-71123

A buffer overflow warning was found in the Linux kernel's ext4 filesystem. In parse_apply_sb_mount_options(), strscpy_pad() is incorrectly used to copy a potentially non-NUL-terminated string (s_mount_opts from superblock) into a NUL-terminated buffer. When the source string lacks NUL termination, FORTIFY_SOURCE detects a buffer overflow as strnlen reads 65 bytes from a 64-byte buffer.

This vulnerability was discovered by syzkaller and affects ext4 filesystem mount operations when the superblock contains improperly formatted mount options. The FORTIFY_SOURCE mechanism detects and reports the overflow, generating a kernel warning. The issue can be triggered by mounting a specially crafted ext4 filesystem image.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.