Re: CVE-2024-42082: xdp: Remove WARN() from __xdp_reg_mem_model()

[Shung-Hsi Yu]

On Tue, Aug 06, 2024 at 10:55:00AM GMT, Greg Kroah-Hartman wrote:
> On Tue, Aug 06, 2024 at 04:48:56PM +0800, Shung-Hsi Yu wrote:
> > On Mon, Jul 29, 2024 at 05:53:11PM GMT, Greg Kroah-Hartman wrote:
> > > Description
> > > ===========
> > > 
> > > In the Linux kernel, the following vulnerability has been resolved:
> > > 
> > > xdp: Remove WARN() from __xdp_reg_mem_model()
> > > 
> > > syzkaller reports a warning in __xdp_reg_mem_model().
> > > 
> > > The warning occurs only if __mem_id_init_hash_table() returns an error. It
> > > returns the error in two cases:
> > > 
> > >   1. memory allocation fails;
> > >   2. rhashtable_init() fails when some fields of rhashtable_params
> > >      struct are not initialized properly.
> > > 
> > > The second case cannot happen since there is a static const rhashtable_params
> > > struct with valid fields. So, warning is only triggered when there is a
> > > problem with memory allocation.
> > > 
> > > Thus, there is no sense in using WARN() to handle this error and it can be
> > > safely removed.
> > [...]
> > 
> > The mention fix (below) simply removed a WARN_ON(1) call, so I believe
> > there's no security implication here.
> 
> If memory allocation fails, and panic-on-warn is enabled, this will
> cause the machine to reboot, hence the need for a CVE allocation.

I had not considered that. Thanks for the explanation.

Shung-Hsi