diff options
| author | Sagi Grimberg <sagi@grimberg.me> | 2024-05-27 22:38:52 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-07-11 13:49:21 +0300 |
| commit | 5502c1f1d0d7472706cc1f201aecf1c935d302d1 (patch) | |
| tree | eca8019aeb940a79683df17bf031c4ff30a96105 | |
| parent | f61cea47ad6fc870b1f2850454c228bf12834fe7 (diff) | |
| download | linux-5502c1f1d0d7472706cc1f201aecf1c935d302d1.tar.xz | |
nvmet: fix a possible leak when destroy a ctrl during qp establishment
[ Upstream commit c758b77d4a0a0ed3a1292b3fd7a2aeccd1a169a4 ]
In nvmet_sq_destroy we capture sq->ctrl early and if it is non-NULL we
know that a ctrl was allocated (in the admin connect request handler)
and we need to release pending AERs, clear ctrl->sqs and sq->ctrl
(for nvme-loop primarily), and drop the final reference on the ctrl.
However, a small window is possible where nvmet_sq_destroy starts (as
a result of the client giving up and disconnecting) concurrently with
the nvme admin connect cmd (which may be in an early stage). But *before*
kill_and_confirm of sq->ref (i.e. the admin connect managed to get an sq
live reference). In this case, sq->ctrl was allocated however after it was
captured in a local variable in nvmet_sq_destroy.
This prevented the final reference drop on the ctrl.
Solve this by re-capturing the sq->ctrl after all inflight request has
completed, where for sure sq->ctrl reference is final, and move forward
based on that.
This issue was observed in an environment with many hosts connecting
multiple ctrls simoutanuosly, creating a delay in allocating a ctrl
leading up to this race window.
Reported-by: Alex Turin <alex@vastdata.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/nvme/target/core.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c index ce7e945cb4f7..cfba3ec7add8 100644 --- a/drivers/nvme/target/core.c +++ b/drivers/nvme/target/core.c @@ -806,6 +806,15 @@ void nvmet_sq_destroy(struct nvmet_sq *sq) percpu_ref_exit(&sq->ref); nvmet_auth_sq_free(sq); + /* + * we must reference the ctrl again after waiting for inflight IO + * to complete. Because admin connect may have sneaked in after we + * store sq->ctrl locally, but before we killed the percpu_ref. the + * admin connect allocates and assigns sq->ctrl, which now needs a + * final ref put, as this ctrl is going away. + */ + ctrl = sq->ctrl; + if (ctrl) { /* * The teardown flow may take some time, and the host may not |