Why Geth Crashes with a LevelDB Index‑Out‑of‑Range Error and How to Fix It

Exception Information

The node logs show a panic with the message panic: runtime error: index out of range and a stack trace pointing to LevelDB utilities in the Geth source.

Exception Analysis

The problematic code resides in shortenb inside vendor/github.com/syndtr/goleveldb/leveldb/util/util.go. The function formats byte sizes using an array of unit strings:

var bunits = [...]string{"", "Ki", "Mi", "Gi"}

func shortenb(bytes int) string {
    i := 0
    for ; bytes > 1024 && i < 4; i++ {
        bytes /= 1024
    }
    return fmt.Sprintf("%d%sB", bytes, bunits[i])
}

The loop limits i to 4, but the bunits slice only has four elements (indices 0‑3). When bytes exceeds 1024*1024*1024*1024 (i.e., reaches terabytes), i becomes 4, causing an out‑of‑range access.

Solution

Two practical fixes are suggested:

Extend the unit array by adding a "Ti" entry, e.g., var bunits = [...]string{"", "Ki", "Mi", "Gi", "Ti"}. This requires verifying that other parts of the code can handle the new unit.

Adjust the loop bound to stop at i < 3, ensuring the index never exceeds the existing slice:

var bunits = [...]string{"", "Ki", "Mi", "Gi"}

func shortenb(bytes int) string {
    i := 0
    for ; bytes > 1024 && i < 3; i++ {
        bytes /= 1024
    }
    return fmt.Sprintf("%d%sB", bytes, bunits[i])
}

This makes the function fall back to "GB" for values larger than a gigabyte, which matches the original maximum unit.

After applying either change, rebuild Geth and test with data volumes that reach the terabyte range to confirm the issue is resolved.