From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-mm <linux-mm@kvack.org>,
Andrea Arcangeli <aarcange@redhat.com>,
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: Wed, 21 Aug 2019 08:53:17 +0800 [thread overview]
Message-ID: <d2bf0b99-2cdd-7868-e5ad-8c2cad4681c2@huawei.com> (raw)
In-Reply-To: <20190820160237.GB4983@redhat.com>
On 2019/8/21 0:02, 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(-)
Tested on lts4.4 and 5.3-rc4, Thanks.
next prev parent reply other threads:[~2019-08-21 0:53 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
2019-08-21 0:53 ` Kefeng Wang [this message]
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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