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Subject[PATCH] char: tpm: vtpm_proxy: Fix race in init
Date
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).

Fixes: 6f99612e2500 ("tpm: Proxy driver for supporting multiple emulated TPMs")
Signed-off-by: Saubhik Mukherjee <saubhik.mukherjee@gmail.com>
---
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
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