Simplify lifetime management of BDRVNBDState->connection_thread by
delaying the possible cleanup of it until the BDRVNBDState itself goes
away.
This also fixes possible use-after-free in nbd_co_establish_connection
when it races with nbd_co_establish_connection_cancel.
Signed-off-by: Roman Kagan
---
This is a more future-proof version of the fix for use-after-free but
less intrusive than Vladimir's series so that it can go in 6.0.
block/nbd.c | 58 ++---
1 file changed, 29 insertions(+), 29 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index d86df3afcb..6e3879c0c5 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -144,16 +144,31 @@ typedef struct BDRVNBDState {
NBDConnectThread *connect_thread;
} BDRVNBDState;
+static void nbd_free_connect_thread(NBDConnectThread *thr);
static int nbd_establish_connection(BlockDriverState *bs, SocketAddress *saddr,
Error **errp);
static int nbd_co_establish_connection(BlockDriverState *bs, Error **errp);
-static void nbd_co_establish_connection_cancel(BlockDriverState *bs,
- bool detach);
+static void nbd_co_establish_connection_cancel(BlockDriverState *bs);
static int nbd_client_handshake(BlockDriverState *bs, Error **errp);
static void nbd_yank(void *opaque);
static void nbd_clear_bdrvstate(BDRVNBDState *s)
{
+NBDConnectThread *thr = s->connect_thread;
+bool thr_running;
+
+qemu_mutex_lock(>mutex);
+thr_running = thr->state == CONNECT_THREAD_RUNNING;
+if (thr_running) {
+thr->state = CONNECT_THREAD_RUNNING_DETACHED;
+}
+qemu_mutex_unlock(>mutex);
+
+/* the runaway thread will clean it up itself */
+if (!thr_running) {
+nbd_free_connect_thread(thr);
+}
+
object_unref(OBJECT(s->tlscreds));
qapi_free_SocketAddress(s->saddr);
s->saddr = NULL;
@@ -293,7 +308,7 @@ static void coroutine_fn
nbd_client_co_drain_begin(BlockDriverState *bs)
qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
}
-nbd_co_establish_connection_cancel(bs, false);
+nbd_co_establish_connection_cancel(bs);
reconnect_delay_timer_del(s);
@@ -333,7 +348,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
if (s->connection_co_sleep_ns_state) {
qemu_co_sleep_wake(s->connection_co_sleep_ns_state);
}
-nbd_co_establish_connection_cancel(bs, true);
+nbd_co_establish_connection_cancel(bs);
}
if (qemu_in_coroutine()) {
s->teardown_co = qemu_coroutine_self();
@@ -534,18 +549,12 @@ nbd_co_establish_connection(BlockDriverState *bs, Error
**errp)
* nbd_co_establish_connection_cancel
* Cancel nbd_co_establish_connection asynchronously: it will finish soon, to
* allow drained section to begin.
- *
- * If detach is true, also cleanup the state (or if thread is running, move it
- * to CONNECT_THREAD_RUNNING_DETACHED state). s->connect_thread becomes NULL if
- * detach is true.
*/
-static void nbd_co_establish_connection_cancel(BlockDriverState *bs,
- bool detach)
+static void nbd_co_establish_connection_cancel(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
NBDConnectThread *thr = s->connect_thread;
bool wake = false;
-bool do_free = false;
qemu_mutex_lock(>mutex);
@@ -556,21 +565,10 @@ static void
nbd_co_establish_connection_cancel(BlockDriverState *bs,
s->wait_connect = false;
wake = true;
}
-if (detach) {
-thr->state = CONNECT_THREAD_RUNNING_DETACHED;
-s->connect_thread = NULL;
-}
-} else if (detach) {
-do_free = true;
}
qemu_mutex_unlock(>mutex);
-if (do_free) {
-nbd_free_connect_thread(thr);
-s->connect_thread = NULL;
-}
-
if (wake) {
aio_co_wake(s->connection_co);
}
@@ -2294,31 +2292,33 @@ static int nbd_open(BlockDriverState *bs, QDict
*options, int flags,
return -EEXIST;
}
+nbd_init_connect_thread(s);
+
/*
* establish TCP connection, return error if it fails
* TODO: Configurable retry-until-timeout behaviour.
*/
if (nbd_establish_connection(bs, s->saddr, errp) < 0) {
-yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name));
-return -ECONNREFUSED;
+ret = -ECONNREFUSED;
+goto fail;
}
ret = nbd_client_handshake(bs, errp);
if (ret < 0) {
-yank_unregister_instance(BLOCKDEV_YANK_INSTANCE(bs->node_name));
-nbd_clear_bdrvstate(s);
-return ret;
+goto fail;
}
/* successfully connected */
s->state = NBD_CLIENT_CONNECTED;
-nbd_init_connect_thread(s);
-
s->connection_co = qemu_coroutine_create(nbd_connection_entry, s);
bdrv_inc_in_flight(bs);
aio_co_schedule(bdrv_get_aio_context(bs),
