[SSHD-699] Server receiving 0-length SSH_MSG_IGNORE causes Buffer Underflow exception

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.2.0
• Fix Version/s: 1.3.0
• Assignee: Lyor Goldstein
• Reporter: Johan Östling
• Created: 16/Sep/16 13:19
• Updated: 16/Sep/16 15:27
• Resolved: 16/Sep/16 15:25

Description

Trying to establish the length of a message with only a header byte will cause a buffer underflow exception. I noticed it on SSH_MSG_IGNORE, but it is probably general to all messages.

Reproducible with unit test:

AbstractSessionTest.java

    @Test
    public void testZeroLengthIgnoreMessage() throws Exception {
        Buffer msg = session.createBuffer(SshConstants.SSH_MSG_IGNORE, Byte.SIZE);
        session.handleIgnore(msg);
    }

This is a regression since 0.14.0, which did not have this problem.