linux-hardening - [PATCH 62/82] mwifiex: pcie: Refactor intentional wrap-around test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240123002814.1396804-62-keescook@chromium.org>
Date: Mon, 22 Jan 2024 16:27:37 -0800
From: Kees Cook <keescook@...omium.org>
To: linux-hardening@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
	Brian Norris <briannorris@...omium.org>,
	Kalle Valo <kvalo@...nel.org>,
	Jonas Dreßler <verdre@...d.nl>,
	Dmitry Antipov <dmantipov@...dex.ru>,
	Tsuchiya Yuto <kitakar@...il.com>,
	linux-wireless@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Bill Wendling <morbo@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 62/82] mwifiex: pcie: Refactor intentional wrap-around test

In an effort to separate intentional arithmetic wrap-around from
unexpected wrap-around, we need to refactor places that depend on this
kind of math. One of the most common code patterns of this is:

	VAR + value < VAR

Notably, this is considered "undefined behavior" for signed and pointer
types, which the kernel works around by using the -fno-strict-overflow
option in the build[1] (which used to just be -fwrapv). Regardless, we
want to get the kernel source to the position where we can meaningfully
instrument arithmetic wrap-around conditions and catch them when they
are unexpected, regardless of whether they are signed[2], unsigned[3],
or pointer[4] types.

Refactor open-coded wrap-around addition test to use add_would_overflow().
This paves the way to enabling the wrap-around sanitizers in the future.

Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1]
Link: https://github.com/KSPP/linux/issues/26 [2]
Link: https://github.com/KSPP/linux/issues/27 [3]
Link: https://github.com/KSPP/linux/issues/344 [4]
Cc: Brian Norris <briannorris@...omium.org>
Cc: Kalle Valo <kvalo@...nel.org>
Cc: "Jonas Dreßler" <verdre@...d.nl>
Cc: Dmitry Antipov <dmantipov@...dex.ru>
Cc: Tsuchiya Yuto <kitakar@...il.com>
Cc: linux-wireless@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 drivers/net/wireless/marvell/mwifiex/pcie.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c b/drivers/net/wireless/marvell/mwifiex/pcie.c
index 5f997becdbaa..e69347e65f0e 100644
--- a/drivers/net/wireless/marvell/mwifiex/pcie.c
+++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
@@ -2086,7 +2086,7 @@ static int mwifiex_extract_wifi_fw(struct mwifiex_adapter *adapter,
 
 		switch (dnld_cmd) {
 		case MWIFIEX_FW_DNLD_CMD_1:
-			if (offset + data_len < data_len) {
+			if (add_would_overflow(data_len, offset)) {
 				mwifiex_dbg(adapter, ERROR, "bad FW parse\n");
 				ret = -1;
 				goto done;
@@ -2110,7 +2110,7 @@ static int mwifiex_extract_wifi_fw(struct mwifiex_adapter *adapter,
 		case MWIFIEX_FW_DNLD_CMD_5:
 			first_cmd = true;
 			/* Check for integer overflow */
-			if (offset + data_len < data_len) {
+			if (add_would_overflow(data_len, offset)) {
 				mwifiex_dbg(adapter, ERROR, "bad FW parse\n");
 				ret = -1;
 				goto done;
@@ -2120,7 +2120,7 @@ static int mwifiex_extract_wifi_fw(struct mwifiex_adapter *adapter,
 		case MWIFIEX_FW_DNLD_CMD_6:
 			first_cmd = true;
 			/* Check for integer overflow */
-			if (offset + data_len < data_len) {
+			if (add_would_overflow(data_len, offset)) {
 				mwifiex_dbg(adapter, ERROR, "bad FW parse\n");
 				ret = -1;
 				goto done;
-- 
2.34.1