ACPI: battery: Fix missing NUL-termination with large strings

stable inclusion
from stable-v4.19.276
commit 6671af7f52c382963b482c6ae55f3e6ee582e0f6
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6TIG1
CVE: NA

--------------------------------

[ Upstream commit f2ac14b5 ]

When encountering a string bigger than the destination buffer (32 bytes),
the string is not properly NUL-terminated, causing buffer overreads later.

This for example happens on the Inspiron 3505, where the battery
model name is larger than 32 bytes, which leads to sysfs showing
the model name together with the serial number string (which is
NUL-terminated and thus prevents worse).

Fix this by using strscpy() which ensures that the result is
always NUL-terminated.

Fixes: 106449e8 ("ACPI: Battery: Allow extract string from integer")
Signed-off-by: NArmin Wolf <W_Armin@gmx.de>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

drivers/acpi/battery.c

@@ -448,7 +448,7 @@ static int extract_package(struct acpi_battery *battery,
 			u8 *ptr = (u8 *)battery + offsets[i].offset;
 			if (element->type == ACPI_TYPE_STRING ||
 			    element->type == ACPI_TYPE_BUFFER)
-				strncpy(ptr, element->string.pointer, 32);
+				strscpy(ptr, element->string.pointer, 32);
 			else if (element->type == ACPI_TYPE_INTEGER) {
 				strncpy(ptr, (u8 *)&element->integer.value,
 					sizeof(u64));