Re: Please consider backporting coredump %F patch to stable kernels

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Jun 02, 2025 at 11:09:05AM +0200, Christian Brauner wrote:
> On Fri, May 30, 2025 at 10:44:16AM +0100, Luca Boccassi wrote:
> > Dear stable maintainer(s),
> > 
> > The following series was merged for 6.16:
> > 
> > https://lore.kernel.org/all/20250414-work-coredump-v2-0-685bf231f828@kernel.org/
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c57f07b235871c9e5bffaccd458dca2d9a62b164
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=95c5f43181fe9c1b5e5a4bd3281c857a5259991f
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b5325b2a270fcaf7b2a9a0f23d422ca8a5a8bdea
> > 
> > This allows the userspace coredump handler to get a PIDFD referencing
> > the crashed process.
> > 
> > We have discovered that there are real world exploits that can be used
> > to trick coredump handling userspace software to act on foreign
> > processes due to PID reuse attacks:
> > 
> > https://security-tracker.debian.org/tracker/CVE-2025-4598
> > 
> > We have fixed the worst case scenario, but to really and
> > comprehensively fix the whole problem we need this new %F option. We
> > have backported the userspace side to the systemd stable branch. Would
> > it be possible to backport the above 3 patches to at least the 6.12
> > series, so that the next Debian stable can be fully covered? The first
> > two are small bug fixes so it would be good to have them, and the
> > third one is quite small and unless explicitly configured in the
> > core_pattern, it will be inert, so risk should be low.
> 
> I agree that we should try and backport this if Greg agrees we can do
> this. v6.15 will be easy to do. Further back might need some custom work
> though. Let's see what Greg thinks.

Yes, seems like a good thing to backport to at least 6.12.y if possible.

Is it just the above 3 commits?

thanks,

greg k-h