wil6210: fix memory access violation in wil_memcpy_from/toio_32

In case count is not multiple of 4, there is a read access in
wil_memcpy_toio_32() from outside src buffer boundary.
In wil_memcpy_fromio_32(), in case count is not multiple of 4, there is
a write access to outside dst io memory boundary.

Fix these issues with proper handling of the last 1 to 4 copied bytes.

Signed-off-by: Dedy Lansky <qca_dlansky@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/wil6210/main.c

@@ -130,9 +130,15 @@ void wil_memcpy_fromio_32(void *dst, const volatile void __iomem *src,
 	u32 *d = dst;
 	const volatile u32 __iomem *s = src;
 
-	/* size_t is unsigned, if (count%4 != 0) it will wrap */
-	for (count += 4; count > 4; count -= 4)
+	for (; count >= 4; count -= 4)
 		*d++ = __raw_readl(s++);
+
+	if (unlikely(count)) {
+		/* count can be 1..3 */
+		u32 tmp = __raw_readl(s);
+
+		memcpy(d, &tmp, count);
+	}
 }
 
 void wil_memcpy_fromio_halp_vote(struct wil6210_priv *wil, void *dst,
@@ -149,8 +155,16 @@ void wil_memcpy_toio_32(volatile void __iomem *dst, const void *src,
 	volatile u32 __iomem *d = dst;
 	const u32 *s = src;
 
-	for (count += 4; count > 4; count -= 4)
+	for (; count >= 4; count -= 4)
 		__raw_writel(*s++, d++);
+
+	if (unlikely(count)) {
+		/* count can be 1..3 */
+		u32 tmp = 0;
+
+		memcpy(&tmp, s, count);
+		__raw_writel(tmp, d);
+	}
 }
 
 void wil_memcpy_toio_halp_vote(struct wil6210_priv *wil,