linux-kernel - [PATCH v2] kobject: fix possible memory leak in kset_create_and

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Date:   Mon, 17 Oct 2022 20:14:46 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <gregkh@...uxfoundation.org>, <rafael@...nel.org>
Subject: [PATCH v2] kobject: fix possible memory leak in kset_create_and_add()

Inject fault while probing module (e.g. qemu_fw_cfg.ko), kset_register()
may fail in kset_create_and_add(), if it fails, but the refcount of kobject
is not decreased to 0, the name allocated in kset_create() is leaked. To fix
this by calling kset_put(), so that name can be freed in callback function
kobject_cleanup() and kset can be freed in kset_release().

unreferenced object 0xffff888103cc8c08 (size 8):
  comm "modprobe", pid 508, jiffies 4294915182 (age 120.020s)
  hex dump (first 8 bytes):
    62 79 5f 6e 61 6d 65 00                          by_name.
  backtrace:
    [<00000000572f97f9>] __kmalloc_track_caller+0x1ae/0x320
    [<00000000a167a5cc>] kstrdup+0x3a/0x70
    [<000000001cd0d05e>] kstrdup_const+0x68/0x80
    [<00000000b9101e6d>] kvasprintf_const+0x10b/0x190
    [<0000000088f2b8df>] kobject_set_name_vargs+0x56/0x150
    [<000000003f8aca68>] kobject_set_name+0xab/0xe0
    [<00000000249f7816>] kset_create_and_add+0x72/0x200

Fixes: b727c702896f ("kset: add kset_create_and_add function")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
v1 -> v2:
  Update commit message.
---
 lib/kobject.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/kobject.c b/lib/kobject.c
index a0b2dbfcfa23..f5e943c9027b 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -982,7 +982,7 @@ struct kset *kset_create_and_add(const char *name,
 		return NULL;
 	error = kset_register(kset);
 	if (error) {
-		kfree(kset);
+		kset_put(kset);
 		return NULL;
 	}
 	return kset;
-- 
2.25.1