linux-kernel - [PATCH 1/4] ACPI: battery: Fix missing NUL-termination with large strings

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Message-Id: <20230114085053.72059-2-W_Armin@gmx.de>
Date:   Sat, 14 Jan 2023 09:50:50 +0100
From:   Armin Wolf <W_Armin@....de>
To:     rafael@...nel.org, lenb@...nel.org
Cc:     linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] ACPI: battery: Fix missing NUL-termination with large strings

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.

Signed-off-by: Armin Wolf <W_Armin@....de>
---
 drivers/acpi/battery.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index f4badcdde76e..fb64bd217d82 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -440,7 +440,7 @@ static int extract_package(struct acpi_battery *battery,

 			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));
--
2.30.2