diff mbox series

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

Message ID 20240123002814.1396804-62-keescook@chromium.org (mailing list archive)
State Changes Requested
Headers show
Series overflow: Refactor open-coded arithmetic wrap-around | expand

Commit Message

Kees Cook Jan. 23, 2024, 12:27 a.m. UTC
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@chromium.org>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: "Jonas Dreßler" <verdre@v0yd.nl>
Cc: Dmitry Antipov <dmantipov@yandex.ru>
Cc: Tsuchiya Yuto <kitakar@gmail.com>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/wireless/marvell/mwifiex/pcie.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Kalle Valo Jan. 23, 2024, 6:36 a.m. UTC | #1
Kees Cook <keescook@chromium.org> writes:

> 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@chromium.org>
> Cc: Kalle Valo <kvalo@kernel.org>
> Cc: "Jonas Dreßler" <verdre@v0yd.nl>
> Cc: Dmitry Antipov <dmantipov@yandex.ru>
> Cc: Tsuchiya Yuto <kitakar@gmail.com>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

I assume this goes via some other tree than wireless-next so:

Acked-by: Kalle Valo <kvalo@kernel.org>
diff mbox series

Patch

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;