[PATCH] comedi: Fix potential memory leak in comedi_init()

From: Shang XiaoJing
Date: Mon Oct 31 2022 - 23:22:48 EST


comedi_init() will goto out_unregister_chrdev_region if cdev_add()
failed, which won't free the resource alloced in kobject_set_name().
Call kfree_const() to free the leaked name before goto
out_unregister_chrdev_region.

unreferenced object 0xffff8881000fa8c0 (size 8):
comm "modprobe", pid 239, jiffies 4294905173 (age 51.308s)
hex dump (first 8 bytes):
63 6f 6d 65 64 69 00 ff comedi..
backtrace:
[<000000005f9878f7>] __kmalloc_node_track_caller+0x4c/0x1c0
[<000000000fd70302>] kstrdup+0x3f/0x70
[<000000009428bc33>] kstrdup_const+0x46/0x60
[<00000000ed50d9de>] kvasprintf_const+0xdb/0xf0
[<00000000b2766964>] kobject_set_name_vargs+0x3c/0xe0
[<00000000f2424ef7>] kobject_set_name+0x62/0x90
[<000000005d5a125b>] 0xffffffffa0013098
[<00000000f331e663>] do_one_initcall+0x7a/0x380
[<00000000aa7bac96>] do_init_module+0x5c/0x230
[<000000005fd72335>] load_module+0x227d/0x2420
[<00000000ad550cf1>] __do_sys_finit_module+0xd5/0x140
[<00000000069a60c5>] do_syscall_64+0x3f/0x90
[<00000000c5e0d521>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: ed9eccbe8970 ("Staging: add comedi core")
Signed-off-by: Shang XiaoJing <shangxiaojing@xxxxxxxxxx>
---
drivers/comedi/comedi_fops.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index e2114bcf815a..2c508c2cf6f6 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -3379,8 +3379,11 @@ static int __init comedi_init(void)

retval = cdev_add(&comedi_cdev, MKDEV(COMEDI_MAJOR, 0),
COMEDI_NUM_MINORS);
- if (retval)
+ if (retval) {
+ kfree_const(comedi_cdev.kobj.name);
+ comedi_cdev.kobj.name = NULL;
goto out_unregister_chrdev_region;
+ }

comedi_class = class_create(THIS_MODULE, "comedi");
if (IS_ERR(comedi_class)) {
--
2.17.1