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@xxxxxxxxxx> Cc: Johannes Berg <johannes.berg@xxxxxxxxx> Cc: Max Chen <mxchen@xxxxxxxxxxxxxx> Cc: Yang Shen <shenyang39@xxxxxxxxxx> Cc: linux-wireless@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- drivers/net/wireless/ath/wil6210/wmi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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; -- 2.34.1
