From: Roman Kagan <rvkagan@yandex-team.ru>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>,
yc-core@yandex-team.ru
Subject: [PATCH 1/7] block/nbd: avoid touching freed connect_thread
Date: Mon, 15 Mar 2021 09:06:05 +0300 [thread overview]
Message-ID: <20210315060611.2989049-2-rvkagan@yandex-team.ru> (raw)
In-Reply-To: <20210315060611.2989049-1-rvkagan@yandex-team.ru>
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>
---
block/nbd.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/block/nbd.c b/block/nbd.c
index c26dc5a54f..447d176b76 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -486,6 +486,15 @@ nbd_co_establish_connection(BlockDriverState *bs, Error **errp)
s->wait_connect = true;
qemu_coroutine_yield();
+ /*
+ * If nbd_co_establish_connection_cancel had a chance to run it may have
+ * invalidated ->connect_thread.
+ */
+ thr = s->connect_thread;
+ if (!thr) {
+ return -ECONNABORTED;
+ }
+
qemu_mutex_lock(&thr->mutex);
switch (thr->state) {
--
2.30.2
next prev parent reply other threads:[~2021-03-15 6:14 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 ` Roman Kagan [this message]
2021-03-15 15:40 ` [PATCH 1/7] block/nbd: avoid touching freed connect_thread Vladimir Sementsov-Ogievskiy
2021-03-16 15:29 ` Roman Kagan
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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