linux-kernel - [PATCH v2 0/2] ACPI: battery: Fix various string handling issues

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Message-Id: <20230119142115.38260-1-W_Armin@gmx.de>
Date:   Thu, 19 Jan 2023 15:21:13 +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 v2 0/2] ACPI: battery: Fix various string handling issues

On my Dell Inspiron 3505, the battery model name was displayed
differently than when running Windows. While i first suspected an
ACPI issue, it turned out that the real reason was the ACPI battery
driver failing to handle strings larger than 32 bytes.

This caused the model name of the battery (35 bytes long, hex string)
to miss proper NUL-termination, resulting in a buffer overread later.
Luckily, a valid string was stored right after the now invalid string,
appending only the battery serial number to the original model name.

The first patch fixes a potential buffer overread then handling buffers,
while the second patch finally increases the maximum string length to
avoid truncating such larger strings.

The patch series was tested on a Dell Inspiron 3505 and appears
to work properly.
---
Changes in v2:
- Drop first patch since it was already applied
- combine the second and third patch
- do not replace 0 with '\0'
- spell ACPI in capitals
- rework the buffer length hdanling

Armin Wolf (2):
  ACPI: battery: Fix buffer overread if not NUL-terminated
  ACPI: battery: Increase maximum string length

 drivers/acpi/battery.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

--
2.30.2