Commit 2236ef18 authored by Sagi Grimberg's avatar Sagi Grimberg Committed by Chen Jun
Browse files

nvmet: fix a possible leak when destroy a ctrl during qp establishment 

stable inclusion
from stable-v5.10.222
commit 2f3c22b1d3d7e86712253244797a651998c141fa
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAGSQU
CVE: CVE-2024-42152

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2f3c22b1d3d7e86712253244797a651998c141fa



--------------------------------

[ 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: default avatarAlex Turin <alex@vastdata.com>
Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarChen Jun <chenjun102@huawei.com>
parent 31421c83

drivers/nvme/target/core.c

+9 −0
Original line number Diff line number Diff line
@@ -795,6 +795,15 @@ void nvmet_sq_destroy(struct nvmet_sq *sq) 
	wait_for_completion(&sq->free_done);

	percpu_ref_exit(&sq->ref);



	/*

	 * 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