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 49C2A17CA0E; Tue, 16 Jul 2024 16:09:11 +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=1721146151; cv=none; b=BcYNFaXoto/gmy2Fq0p465u75E26sVweLQXBro1iXMyvYTAvTu2BKQgLIc7eBxPv83584YEknnAJjiFRF/tauwvPJ92K0aKklUcz8FCn7AFZfRyLwHH9AMlbWJwMS/ShkQQETdaG8Lv/mq161V7v+AkvXfgcZovBBLl3je2dWxY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721146151; c=relaxed/simple; bh=mQMz37MbU8o46Sql0S9/D1FXpiIShrMPeZnK1M4yKkM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DbgmKoPVjcZE3ahEz296Q+mKCeaHx2VjszZmdzESGqFF5VuT31Dj4/RwqSpBsAejpx/KxWV9EiLb7HI1yY7vjtjkBCrSEBGT25M+uwd3PSOxQbtzKZpQX0QiCFVGQxfU+i4hiG1KtzzAaawj/EFk8VrhOaLiI4C+l7GZmG1QCXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aGvteOaJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aGvteOaJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85446C116B1; Tue, 16 Jul 2024 16:09:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1721146150; bh=mQMz37MbU8o46Sql0S9/D1FXpiIShrMPeZnK1M4yKkM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aGvteOaJ0gTUxTHQrM3CRNRURCr4e2PstpS3qGnzHw8psvlAU0iLW3ZUP4U2NLSmM rg7jsrOZns+XxKvLxuQGK//aTB/ddp+UuZsiZkiK54aoRWb8ystgmNCuup3er5rnPP Egt6C7RMmYsaFqnOo3GeWO8vVfGZnBBnHraI460U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alex Turin , Sagi Grimberg , Christoph Hellwig , Keith Busch , Sasha Levin Subject: [PATCH 5.15 074/144] nvmet: fix a possible leak when destroy a ctrl during qp establishment Date: Tue, 16 Jul 2024 17:32:23 +0200 Message-ID: <20240716152755.390468821@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240716152752.524497140@linuxfoundation.org> References: <20240716152752.524497140@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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 2c44d5a95c8d6..ef2e500bccfdf 100644 --- a/drivers/nvme/target/core.c +++ b/drivers/nvme/target/core.c @@ -801,6 +801,15 @@ 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 -- 2.43.0