Re: CVE request: kernel: open() call allows setgid bit when user is not in new file's group

["Steven M. Christey" <coley () linus mitre org>]

On Wed, 24 Sep 2008, Eugene Teo wrote:

> "When creating a file, open()/creat() allows the setgid bit to be set
> via the mode argument even when, due to the bsdgroups mount option or
> the file being created in a setgid directory, the new file's group is
> one which the user is not a member of.  The user can then use
> ftruncate() and memory-mapped I/O to turn the new file into an arbitrary
> binary and thus gain the privileges of this group, since these
> operations do not clear the setgid bit."

Use CVE-2008-4210, to  be filled in later.

- Steve