Mozilla Foundation Security Advisory 2012-40

Buffer overflow and use-after-free issues found using Address Sanitizer

June 5, 2012
Abhishek Arya
Firefox, Firefox ESR, SeaMonkey, Thunderbird, Thunderbird ESR
Fixed in
  • Firefox 13
  • Firefox ESR 10.0.5
  • SeaMonkey 2.10
  • Thunderbird 13
  • Thunderbird ESR 10.0.5


Security researcher Abhishek Arya of Google used the Address Sanitizer tool to uncover several issues: two heap buffer overflow bugs and a use-after-free problem. The first heap buffer overflow was found in conversion from unicode to native character sets when the function fails. The use-after-free occurs in nsFrameList when working with column layout with absolute positioning in a container that changes size. The second buffer overflow occurs in nsHTMLReflowState when a window is resized on a page with nested columns and a combination of absolute and relative positioning. All three of these issues are potentially exploitable.