steps to reproduce

• Click on 'Comment' in any JIRA ticket
• Click on code to add

  {code} ... {/code}
  

  braces

• insert large (more than 20000 chars) text of any kind into that area

result
JIRA shows 'text too large' message and than browser crashes
FF - eats all available memory and swap (14GB on my PC) and blows
Chrome - eats few GBs of memory and than the tab crashes.

expected
JIRA shows 'text too large' message, browser does not crash