On Wed, Nov 16, 2022 at 01:27:14AM +0000, Chen Jun wrote:
> kmemleak reports memory leaks in watchdog_dev_register, as follows:
> unreferenced object 0xffff888116233000 (size 2048):
> comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s)
> hex dump (first 32 bytes):
> 80 fa b9 05 81 88 ff ff 08 30 23 16 81 88 ff ff .........0#.....
> 08 30 23 16 81 88 ff ff 00 00 00 00 00 00 00 00 .0#.............
> backtrace:
> [<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
> [<000000006a389304>] kmalloc_trace+0x21/0x110
> [<000000008d640eea>] watchdog_dev_register+0x4e/0x780 [watchdog]
> [<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
> [<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
> [<000000001f730178>] 0xffffffffc10880ae
> [<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
> [<00000000b98be325>] do_init_module+0x1ca/0x5f0
> [<0000000046d08e7c>] load_module+0x6133/0x70f0
> ...
>
> unreferenced object 0xffff888105b9fa80 (size 16):
> comm ""modprobe"", pid 28147, jiffies 4353426116 (age 61.741s)
> hex dump (first 16 bytes):
> 77 61 74 63 68 64 6f 67 31 00 b9 05 81 88 ff ff watchdog1.......
> backtrace:
> [<000000007f001ffd>] __kmem_cache_alloc_node+0x157/0x220
> [<00000000486ab89b>] __kmalloc_node_track_caller+0x44/0x1b0
> [<000000005a39aab0>] kvasprintf+0xb5/0x140
> [<0000000024806f85>] kvasprintf_const+0x55/0x180
> [<000000009276cb7f>] kobject_set_name_vargs+0x56/0x150
> [<00000000a92e820b>] dev_set_name+0xab/0xe0
> [<00000000cec812c6>] watchdog_dev_register+0x285/0x780 [watchdog]
> [<0000000053c9f248>] __watchdog_register_device+0x4f0/0x680 [watchdog]
> [<00000000b2979824>] watchdog_register_device+0xd2/0x110 [watchdog]
> [<000000001f730178>] 0xffffffffc10880ae
> [<000000007a1a8bcc>] do_one_initcall+0xcb/0x4d0
> [<00000000b98be325>] do_init_module+0x1ca/0x5f0
> [<0000000046d08e7c>] load_module+0x6133/0x70f0
> ...
>
> The reason is that put_device is not be called if cdev_device_add fails
> and wdd->id != 0.
>
> watchdog_cdev_register
> wd_data = kzalloc [1]
> err = dev_set_name [2]
> ..
> err = cdev_device_add
> if (err) {
> if (wdd->id == 0) { // wdd->id != 0
> ..
> }
> return err; // [1],[2] would be leaked
>
> To fix it, call put_device in all wdd->id cases.
>
> Fixes: 72139dfa2464 ("watchdog: Fix the race between the release of watchdog_core_data and cdev")
> Signed-off-by: Chen Jun <chenjun102@xxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/watchdog/watchdog_dev.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 55574ed42504..fdffa6859dde 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -1061,8 +1061,8 @@ static int watchdog_cdev_register(struct watchdog_device *wdd)
> if (wdd->id == 0) {
> misc_deregister(&watchdog_miscdev);
> old_wd_data = NULL;
> - put_device(&wd_data->dev);
> }
> + put_device(&wd_data->dev);
> return err;
> }
>
> --
> 2.17.1
>
