From: Roman Kagan <rvkagan@yandex-team.ru>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, qemu-devel@nongnu.org,
Max Reitz <mreitz@redhat.com>,
yc-core@yandex-team.ru
Subject: Re: [PATCH 1/7] block/nbd: avoid touching freed connect_thread
Date: Tue, 16 Mar 2021 18:29:18 +0300 [thread overview]
Message-ID: <YFDOzrmp4Hi+cyMJ@rvkaganb.lan> (raw)
In-Reply-To: <b551f5f1-fc80-db3c-57a8-627195048bf4@virtuozzo.com>
On Mon, Mar 15, 2021 at 06:40:12PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> 15.03.2021 09:06, Roman Kagan wrote:
> > When the NBD connection is being torn down, the connection thread gets
> > canceled and "detached", meaning it is about to get freed.
> >
> > If this happens while the connection coroutine yielded waiting for the
> > connection thread to complete, when it resumes it may access the
> > invalidated connection thread data.
> >
> > To prevent this, revalidate the ->connect_thread pointer in
> > nbd_co_establish_connection_cancel before using after the the yield.
> >
> > Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
>
> Seems possible. Do you have a reproducer? Would be great to make an iotest.
It triggered on me in iotest 277, but seems to be timing-dependent.
I'll see if I can do it reliable.
Thanks,
Roman.
next prev parent reply other threads:[~2021-03-16 15:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 6:06 [PATCH 0/7] block/nbd: decouple reconnect from drain Roman Kagan
2021-03-15 6:06 ` [PATCH 1/7] block/nbd: avoid touching freed connect_thread Roman Kagan
2021-03-15 15:40 ` Vladimir Sementsov-Ogievskiy
2021-03-16 15:29 ` Roman Kagan [this message]
2021-04-06 16:21 ` Vladimir Sementsov-Ogievskiy
2021-03-15 6:06 ` [PATCH 2/7] block/nbd: use uniformly nbd_client_connecting_wait Roman Kagan
2021-03-15 15:48 ` Vladimir Sementsov-Ogievskiy
2021-03-15 6:06 ` [PATCH 3/7] block/nbd: assert attach/detach runs in the proper context Roman Kagan
2021-03-15 16:41 ` Vladimir Sementsov-Ogievskiy
2021-03-15 19:57 ` Roman Kagan
2021-03-15 6:06 ` [PATCH 4/7] block/nbd: transfer reconnection stuff across aio_context switch Roman Kagan
2021-03-15 6:06 ` [PATCH 5/7] block/nbd: better document a case in nbd_co_establish_connection Roman Kagan
2021-03-15 6:06 ` [PATCH 6/7] block/nbd: decouple reconnect from drain Roman Kagan
2021-03-15 20:10 ` Vladimir Sementsov-Ogievskiy
2021-03-16 16:03 ` Roman Kagan
2021-03-16 18:09 ` Vladimir Sementsov-Ogievskiy
2021-03-26 6:16 ` Roman Kagan
2021-03-15 6:06 ` [PATCH 7/7] block/nbd: stop manipulating in_flight counter Roman Kagan
2021-03-15 20:15 ` Vladimir Sementsov-Ogievskiy
2021-03-16 16:08 ` Roman Kagan
2021-03-16 18:37 ` Vladimir Sementsov-Ogievskiy
2021-03-26 7:41 ` Roman Kagan
2021-03-15 19:45 ` [PATCH 0/7] block/nbd: decouple reconnect from drain Vladimir Sementsov-Ogievskiy
2021-03-16 15:52 ` Roman Kagan
2021-03-16 14:41 ` Eric Blake
2021-03-16 16:10 ` Roman Kagan
2021-03-17 8:35 ` Vladimir Sementsov-Ogievskiy
2021-03-26 8:07 ` Roman Kagan
2021-04-07 7:45 ` Roman Kagan
2021-04-07 10:13 ` Vladimir Sementsov-Ogievskiy
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