Messages in this thread Patch in this message | | | From | madhuparnabhowmik10@gmail ... | Subject | [PATCH] drivers: isdn: capi: Fix data-race bug | Date | Wed, 22 Jul 2020 22:53:29 +0530 |
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From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
In capi_init(), after register_chrdev() the file operation callbacks can be called. However capinc_tty_init() is called later. Since capiminors and capinc_tty_driver are initialized in capinc_tty_init(), their initialization can race with their usage in various callbacks like in capi_release().
Therefore, call capinc_tty_init() before register_chrdev to avoid such race conditions.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> --- drivers/isdn/capi/capi.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/isdn/capi/capi.c b/drivers/isdn/capi/capi.c index 85767f52fe3c..7e8ab48a15af 100644 --- a/drivers/isdn/capi/capi.c +++ b/drivers/isdn/capi/capi.c @@ -1332,7 +1332,7 @@ static int __init capinc_tty_init(void) return 0; } -static void __exit capinc_tty_exit(void) +static void capinc_tty_exit(void) { tty_unregister_driver(capinc_tty_driver); put_tty_driver(capinc_tty_driver); @@ -1420,29 +1420,28 @@ static int __init capi_init(void) if (ret) return ret; + if (capinc_tty_init() < 0) { + kcapi_exit(); + return -ENOMEM; + } + major_ret = register_chrdev(capi_major, "capi20", &capi_fops); if (major_ret < 0) { printk(KERN_ERR "capi20: unable to get major %d\n", capi_major); + capinc_tty_exit(); kcapi_exit(); return major_ret; } capi_class = class_create(THIS_MODULE, "capi"); if (IS_ERR(capi_class)) { unregister_chrdev(capi_major, "capi20"); + capinc_tty_exit(); kcapi_exit(); return PTR_ERR(capi_class); } device_create(capi_class, NULL, MKDEV(capi_major, 0), NULL, "capi20"); - if (capinc_tty_init() < 0) { - device_destroy(capi_class, MKDEV(capi_major, 0)); - class_destroy(capi_class); - unregister_chrdev(capi_major, "capi20"); - kcapi_exit(); - return -ENOMEM; - } - proc_init(); #ifdef CONFIG_ISDN_CAPI_MIDDLEWARE -- 2.17.1
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