Re: CVE-2015-6937 - Linux kernel - NULL pointer dereference in net/rds/connection.c

[Quentin Casasnovas <quentin.casasnovas () oracle com>]

On Mon, Sep 14, 2015 at 03:34:59PM -0400, cve-assign () mitre org wrote:
> CVE-2015-6937 has been assigned to this issue that is exploitable "on
> sockets that weren't properly bound before attempting to send a
> message":
>
>   https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=74e98eb085889b0d2d4908f59f6e00026063014f

The above fix is incomplete and still allows to trigger a NULL pointer
dereference when sending a message.  The root cause of this problem is a
race condition when checking that the socket is bound in rds_sendmsg(),
more information and a complete fix can be found here:

  https://lkml.org/lkml/2015/10/16/530

It should hit Linus' tree soon but since distributions already started
shipping the incomplete fix, I thought it would be wise to mention this
here.

Quentin