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([103.242.196.10]) by smtp.gmail.com with ESMTPSA id la18sm2767040pjb.55.2021.06.23.06.22.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Jun 2021 06:22:45 -0700 (PDT) From: Saubhik Mukherjee To: peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca Cc: Saubhik Mukherjee , linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, ldv-project@linuxtesting.org, andrianov@ispras.ru Subject: [PATCH] char: tpm: vtpm_proxy: Fix race in init Date: Wed, 23 Jun 2021 18:52:26 +0530 Message-Id: <20210623132226.140341-1-saubhik.mukherjee@gmail.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org vtpm_module_init calls vtpmx_init which calls misc_register. The file operations callbacks are registered. So, vtpmx_fops_ioctl can execute in parallel with rest of vtpm_module_init. vtpmx_fops_ioctl calls vtpmx_ioc_new_dev, which calls vtpm_proxy_create_device, which calls vtpm_proxy_work_start, which could read uninitialized workqueue. To avoid this, create workqueue before vtpmx init. Found by Linux Driver Verification project (linuxtesting.org). Signed-off-by: Saubhik Mukherjee --- drivers/char/tpm/tpm_vtpm_proxy.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c index 91c772e38bb5..225dfa026a8f 100644 --- a/drivers/char/tpm/tpm_vtpm_proxy.c +++ b/drivers/char/tpm/tpm_vtpm_proxy.c @@ -697,23 +697,22 @@ static int __init vtpm_module_init(void) { int rc; - rc = vtpmx_init(); - if (rc) { - pr_err("couldn't create vtpmx device\n"); - return rc; - } - workqueue = create_workqueue("tpm-vtpm"); if (!workqueue) { pr_err("couldn't create workqueue\n"); - rc = -ENOMEM; - goto err_vtpmx_cleanup; + return -ENOMEM; + } + + rc = vtpmx_init(); + if (rc) { + pr_err("couldn't create vtpmx device\n"); + goto err_destroy_workqueue; } return 0; -err_vtpmx_cleanup: - vtpmx_cleanup(); +err_destroy_workqueue: + destroy_workqueue(workqueue); return rc; } -- 2.30.2