Re: CVE-2021-20219 Linux kernel: improper synchronization in flush_to_ldisc() can lead to DoS

[Salvatore Bonaccorso <carnil () debian org>]

Hi Rohit,

On Wed, Mar 17, 2021 at 04:17:05PM +0100, Greg KH wrote:
> On Wed, Mar 17, 2021 at 07:45:59PM +0530, Rohit Keshri wrote:
> > Hello Team,
> >
> > A denial of service vulnerability was found in n_tty_receive_char_special
> > in drivers/tty/n_tty.c of the Linux kernel.  In this flaw a local attacker
> > with a normal user privilege could delay the loop (due to a changing
> > ldata->read_head, and a missing sanity check) and cause a threat to the
> > system availability.
> >
> > 'CVE-2021-20219' was assigned by Red Hat.
> >
> > Acknowledgements: Evgenii Shatokhin (Virtuozzo Research LLC)
>
> Really?  Not the tools or people that reported this issue and fixed it
> in the community back in 2018?

Can you clarify, would 3d63b7e4ae0d ("n_tty: Fix stall at
n_tty_receive_char_special().") be the upstream fix you are referring
to for it?

Regards,
Salvatore