Fix Buffer Overflow in mke2fs test_disk Function

[PwnVerse]

Summary

Fix critical buffer overflow vulnerability in test_disk() function where unbounded sprintf() can write beyond the 1024-byte buffer when processing long device names.

Description

The sprintf() call at line 258 in mke2fs.c constructs a command string without bounds checking:

char buf[1024];
sprintf(buf, "badblocks -b %d -X %s%s%s %llu", fs->blocksize,
    quiet ? "" : "-s ", (cflag > 1) ? "-w " : "",
    fs->device_name,
    (unsigned long long) ext2fs_blocks_count(fs->super)-1);

Potential for stack-based buffer overflow with device names > ~950 characters.

Patch

Replace sprintf() with snprintf() for bounds checking and add proper error handling for oversized command strings.