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Message-ID: <20221017095342.2567-1-chenzhongjin@huawei.com>
Date: Mon, 17 Oct 2022 17:53:42 +0800
From: Chen Zhongjin <chenzhongjin@...wei.com>
To: <linux-kernel@...r.kernel.org>
CC: <gregkh@...uxfoundation.org>, <linmq006@...il.com>,
<chenzhongjin@...wei.com>
Subject: [PATCH] firmware: dmi-sysfs: Fix null-ptr-deref in dmi_sysfs_register_handle
KASAN reported a null-ptr-deref error:
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 1373 Comm: modprobe
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
RIP: 0010:dmi_sysfs_entry_release
...
Call Trace:
<TASK>
kobject_put
dmi_sysfs_register_handle (drivers/firmware/dmi-sysfs.c:540) dmi_sysfs
dmi_decode_table (drivers/firmware/dmi_scan.c:133)
dmi_walk (drivers/firmware/dmi_scan.c:1115)
dmi_sysfs_init (drivers/firmware/dmi-sysfs.c:149) dmi_sysfs
do_one_initcall (init/main.c:1296)
...
Kernel panic - not syncing: Fatal exception
Kernel Offset: 0x4000000 from 0xffffffff81000000
---[ end Kernel panic - not syncing: Fatal exception ]---
It is because previous patch added kobject_put() to release the memory
which will call dmi_sysfs_entry_release() and list_del().
However, list_add_tail(entry->list) is called after the error block,
so the list_head is uninitialized and cannot be deleted.
Because entry is allocated by kzalloc() so the list.prev is NULL in
the error path. Check it in dmi_sysfs_entry_release() to avoid
deleting uninitialized list_head.
Fixes: 660ba678f999 ("firmware: dmi-sysfs: Fix memory leak in dmi_sysfs_register_handle")
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
---
drivers/firmware/dmi-sysfs.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
index 66727ad3361b..f8815eeed00c 100644
--- a/drivers/firmware/dmi-sysfs.c
+++ b/drivers/firmware/dmi-sysfs.c
@@ -557,9 +557,12 @@ static void dmi_sysfs_entry_release(struct kobject *kobj)
{
struct dmi_sysfs_entry *entry = to_entry(kobj);
- spin_lock(&entry_list_lock);
- list_del(&entry->list);
- spin_unlock(&entry_list_lock);
+ if (entry->list.prev != NULL) {
+ spin_lock(&entry_list_lock);
+ list_del(&entry->list);
+ spin_unlock(&entry_list_lock);
+ }
+
kfree(entry);
}
--
2.17.1
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