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Date: Wed, 10 Feb 2021 16:18:20 +0100
From: Alexandros Toptsoglou <atoptsoglou@...e.de>
To: oss-security@...ts.openwall.com, Rohit Keshri <rkeshri@...hat.com>
Subject: Re: CVE-2021-20200: Linux kernel: close race between
 munmap() and expand_upwards()/downwards()

Hi,

is the information listed here correct? Especially the CVE-2021-20200
assignment.

In project-zero reference at the last comment CVE-2020-29369 is mentioned.

Best regards,

Alexandros

On 2/10/21 4:04 PM, Rohit Keshri wrote:
> Hello Team,
> 
> A use-after-free flaw may be seen due to a race problem while in
> detach_vmas_to_be_unmapped() in mm/mmap.c in VMA access while
> munmap(). This flaw could allow a local attacker with a user privilege
> to crash the system, because VMA with VM_GROWSDOWN or VM_GROWSUP flag
> set may change their size under mmap_read_lock(). This vulnerability
> could even lead to a kernel information leak problem.
> 
> 
> 'CVE-2021-20200' was assigned by Red Hat.
> 
> References:
> https://bugs.chromium.org/p/project-zero/issues/detail?id=2056
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=246c320a8cfe0b11d81a4af38fa9985ef0cc9a4c
> 
> Thanks and Regards
> ..
> Rohit Keshri / Red Hat Product Security Team
> PGP: OX01BC 858A 07B7 15C8 EF33 BFE2 2EEB 0CBC 84A4 4C2D
> 
> secalert@...hat.com for urgent response
> 

-- 
Alexandros Toptsoglou <atoptsoglou@...e.de>
Security Engineer
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