diff mbox series

[41/82] wil6210: Refactor intentional wrap-around test

Message ID 20240123002814.1396804-41-keescook@chromium.org
State New
Headers
Series overflow: Refactor open-coded arithmetic wrap-around |

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: Kalle Valo <kvalo@kernel.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Max Chen <mxchen@codeaurora.org>
Cc: Yang Shen <shenyang39@huawei.com>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/wireless/ath/wil6210/wmi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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: Kalle Valo <kvalo@kernel.org>
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Max Chen <mxchen@codeaurora.org>
> Cc: Yang Shen <shenyang39@huawei.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>
Kalle Valo Jan. 23, 2024, 11:50 a.m. UTC | #2 
Kees Cook <keescook@chromium.org> wrote:

> 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: Kalle Valo <kvalo@kernel.org>
> Cc: Johannes Berg <johannes.berg@intel.com>
> Cc: Max Chen <mxchen@codeaurora.org>
> Cc: Yang Shen <shenyang39@huawei.com>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Acked-by: Kalle Valo <kvalo@kernel.org>

If you can edit before commit please add "wifi:" prefix to the wireless patches:

ERROR: 'wifi:' prefix missing: '[PATCH 41/82] wil6210: Refactor intentional wrap-around test'
ERROR: 'wifi:' prefix missing: '[PATCH 62/82] mwifiex: pcie: Refactor intentional wrap-around test'

2 patches set to Not Applicable.

13526631 [41/82] wil6210: Refactor intentional wrap-around test
13526632 [62/82] mwifiex: pcie: Refactor intentional wrap-around test
Kees Cook Jan. 23, 2024, 10:52 p.m. UTC | #3 
On Tue, Jan 23, 2024 at 11:50:34AM +0000, Kalle Valo wrote:
> Kees Cook <keescook@chromium.org> wrote:
> 
> > 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: Kalle Valo <kvalo@kernel.org>
> > Cc: Johannes Berg <johannes.berg@intel.com>
> > Cc: Max Chen <mxchen@codeaurora.org>
> > Cc: Yang Shen <shenyang39@huawei.com>
> > Cc: linux-wireless@vger.kernel.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > Acked-by: Kalle Valo <kvalo@kernel.org>
> 
> If you can edit before commit please add "wifi:" prefix to the wireless patches:
> 
> ERROR: 'wifi:' prefix missing: '[PATCH 41/82] wil6210: Refactor intentional wrap-around test'
> ERROR: 'wifi:' prefix missing: '[PATCH 62/82] mwifiex: pcie: Refactor intentional wrap-around test'

Ah yes, thank you! I will adjust them.

-Kees

> 
> 2 patches set to Not Applicable.
> 
> 13526631 [41/82] wil6210: Refactor intentional wrap-around test
> 13526632 [62/82] mwifiex: pcie: Refactor intentional wrap-around test
> 
> -- 
> https://patchwork.kernel.org/project/linux-wireless/patch/20240123002814.1396804-41-keescook@chromium.org/
> 
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
>
diff mbox series

Patch

diff --git a/drivers/net/wireless/ath/wil6210/wmi.c b/drivers/net/wireless/ath/wil6210/wmi.c
index 6fdb77d4c59e..3b3c991f77e9 100644
--- a/drivers/net/wireless/ath/wil6210/wmi.c
+++ b/drivers/net/wireless/ath/wil6210/wmi.c
@@ -286,7 +286,7 @@  void __iomem *wmi_buffer_block(struct wil6210_priv *wil, __le32 ptr_, u32 size)
 	off = HOSTADDR(ptr);
 	if (off > wil->bar_size - 4)
 		return NULL;
-	if (size && ((off + size > wil->bar_size) || (off + size < off)))
+	if (size && ((off + size > wil->bar_size) || (add_would_overflow(off, size))))
 		return NULL;
 
 	return wil->csr + off;