On Wed, Jun 30, 2021 at 12:54:30PM +0530, Saubhik Mukherjee wrote:

On 6/30/21 2:35 AM, Jarkko Sakkinen wrote:

quoted

On Tue, Jun 29, 2021 at 08:27:00PM +0300, Jarkko Sakkinen wrote:

quoted

On Wed, Jun 23, 2021 at 06:52:26PM +0530, Saubhik Mukherjee wrote:

quoted

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 <redacted>
---
  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

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

Taking reviewed-by back.

You're lacking fixes tag. Please re-send with one.

/Jarkko

Thank you for noticing. I sent the patch containing the Fixes tag in reply
to your last message. (https://lkml.org/lkml/2021/6/30/104)

Please do not do that. Instead, version your patches (git format-patch -vX)
and send them as separate threads.

It's all documented: https://www.kernel.org/doc/html/v5.13/process/submitting-patches.html

/Jarkko