linux-kernel - [PATCH] comedi: Fix potential memory leak in comedi

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Date:   Tue, 1 Nov 2022 11:21:25 +0800
From:   Shang XiaoJing <shangxiaojing@...wei.com>
To:     <abbotti@....co.uk>, <hsweeten@...ionengravers.com>,
        <gregkh@...uxfoundation.org>, <zhangxuezhi1@...lpad.com>,
        <fmhess@...rs.sourceforge.net>, <linux-kernel@...r.kernel.org>
CC:     <shangxiaojing@...wei.com>
Subject: [PATCH] comedi: Fix potential memory leak in comedi_init()

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@...wei.com>
---
 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