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From: Andrea Arcangeli <aarcange@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>,
	linux-mm <linux-mm@kvack.org>, Peter Xu <peterx@redhat.com>,
	Mike Rapoport <rppt@linux.ibm.com>, Jann Horn <jannh@google.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Michal Hocko <mhocko@suse.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx
Date: Tue, 20 Aug 2019 12:05:25 -0400	[thread overview]
Message-ID: <20190820160525.GN31518@redhat.com> (raw)
In-Reply-To: <20190820160237.GB4983@redhat.com>

On Tue, Aug 20, 2019 at 06:02:38PM +0200, Oleg Nesterov wrote:
> userfaultfd_release() should clear vm_flags/vm_userfaultfd_ctx even
> if mm->core_state != NULL.
> 
> Otherwise a page fault can see userfaultfd_missing() == T and use an
> already freed userfaultfd_ctx.
> 
> Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Fixes: 04f5866e41fb ("coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping")
> Cc: stable@vger.kernel.org
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>  fs/userfaultfd.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>

Thanks,
Andrea

  reply	other threads:[~2019-08-20 16:05 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13  9:08 [BUG] kernel BUG at fs/userfaultfd.c:385 after 04f5866e41fb Kefeng Wang
2019-08-14 13:53 ` Michal Hocko
2019-08-14 14:45   ` Kefeng Wang
2019-08-14 15:10     ` Oleg Nesterov
2019-08-14 15:41       ` Oleg Nesterov
2019-08-15  2:21         ` Kefeng Wang
2019-08-15  9:54           ` Oleg Nesterov
2019-08-16 10:37             ` Kefeng Wang
2019-08-19 12:48               ` Oleg Nesterov
2019-08-19 16:05         ` Andrea Arcangeli
2019-08-20 15:59           ` Oleg Nesterov
2019-08-20 16:15             ` Andrea Arcangeli
     [not found]           ` <73d7b5b1-a88c-5fca-ba16-be214c2524a4@I-love.SAKURA.ne.jp>
2019-08-20 16:09             ` Oleg Nesterov
2019-08-20 16:02 ` [PATCH] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx Oleg Nesterov
2019-08-20 16:05   ` Andrea Arcangeli [this message]
2019-08-21  0:53   ` Kefeng Wang
2019-08-27 16:33 ` [BUG] kernel BUG at fs/userfaultfd.c:385 after 04f5866e41fb Oleg Nesterov
2019-08-27 17:14   ` Andrea Arcangeli
2019-08-28 14:25     ` Oleg Nesterov
2019-08-29 12:05       ` Andrea Arcangeli
2019-08-30 16:49         ` Oleg Nesterov

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