From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 069EC1CC711; Wed, 5 Jun 2024 12:05:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717589111; cv=none; b=ZPuHRiWwj1KQkwPqqOwxT+pvpDupQg9kkSTw087GlQLshNVrY8hw2KlEKNIig7kiyqdiiX0yU28TTPR1dX4hmsx9iGWG6kdSIQcjI2+C4WUZWYdLrDcpD9WzosTHMcPpLW0tfh6zFbi/Yd8aSooF2swZ57URjYKQ08/iooqP3/E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717589111; c=relaxed/simple; bh=1RbxT/6OSTDCO1lrHIY3cQWVCBAg91gJZtNuWLxq+Lg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LmSYbienipbDes15XdYOaA7OretGO8ThbOEBg6SvVOhiJTToGgBc1fa35xqYGgfk/TUyRUar2N3WfZ8vreYgORCkfZaBCSJwx2jGMrncsAAeRzruIdLicM7pahwjuLSugBpCHgbxLkYXcplkLkRL7MwgOmHZIU+zt8+38PUWkEE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BUHN7vbw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BUHN7vbw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC0BBC3277B; Wed, 5 Jun 2024 12:05:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717589110; bh=1RbxT/6OSTDCO1lrHIY3cQWVCBAg91gJZtNuWLxq+Lg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BUHN7vbwEFuKf6tNBBko4yWH1H0+PpdN1QsivhfTDoxVm6wbW1Xqg5o3vuyd6GPk4 zII0JXKvyswJXsrwrGBwwlyxobJ3cMkWzECIkLtfbwF+kggE2k6apUIC9Vtpa742fE D0rADZjYuAluI495+QrockfjIjeqgFqfbPaV1odWqax8a1orKHIfbx6tmcAa9PV+vd +AlCdhISaqceQh9WDZkKsMLix1VkRrU5DnA/QVW1zbvlFjjW21+4VhdThkA9KRHiW1 0UfZyquT2XeAFY+utcMeMlqrxFA1indcSORhiYVZxTZ+5Z3A8LyGcyPJ8IjsxDriAb jGCTAWjXi6Y2A== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sagi Grimberg , Alex Turin , Christoph Hellwig , Keith Busch , Sasha Levin , kch@nvidia.com, linux-nvme@lists.infradead.org Subject: [PATCH AUTOSEL 6.1 09/14] nvmet: fix a possible leak when destroy a ctrl during qp establishment Date: Wed, 5 Jun 2024 08:04:42 -0400 Message-ID: <20240605120455.2967445-9-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240605120455.2967445-1-sashal@kernel.org> References: <20240605120455.2967445-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.92 Content-Transfer-Encoding: 8bit From: Sagi Grimberg [ 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 Signed-off-by: Sagi Grimberg Reviewed-by: Christoph Hellwig Signed-off-by: Keith Busch Signed-off-by: Sasha Levin --- drivers/nvme/target/core.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c index 3235baf7cc6b1..c7c8dedf1f47b 100644 --- a/drivers/nvme/target/core.c +++ b/drivers/nvme/target/core.c @@ -802,6 +802,15 @@ 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 -- 2.43.0