[PATCH wireless] wifi: wilc1000: zero-pad SDIO write buffer to block-aligned length

[Tristan Madani]

wilc_sdio_write() rounds up the transfer size to 4 bytes via
ALIGN(size, 4) before passing the buffer to the SDIO controller. When
the original size is not 4-byte aligned, the trailing bytes after the
payload are whatever data happens to occupy that memory, and they get
transmitted to the wireless device firmware.

Zero-pad the trailing bytes before the alignment so that no stale data
is sent over the SDIO bus.

Fixes: c5c77ba18ea6 ("staging: wilc1000: Add SDIO/SPI 802.11 driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tristan Madani <tristan@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/microchip/wilc1000/sdio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/microchip/wilc1000/sdio.c b/drivers/net/wireless/microchip/wilc1000/sdio.c
index 67dea1360f0a8..1a8c7ffcba496 100644
--- a/drivers/net/wireless/microchip/wilc1000/sdio.c
+++ b/drivers/net/wireless/microchip/wilc1000/sdio.c
@@ -441,6 +441,8 @@ static int wilc_sdio_write(struct wilc *wilc, u32 addr, u8 *buf, u32 size)
 		cmd.address = WILC_SDIO_F1_DATA_REG;
 	}
 
+	if (size & 3)
+		memset(buf + size, 0, ALIGN(size, 4) - size);
 	size = ALIGN(size, 4);
 	nblk = size / block_size;
 	nleft = size % block_size;
-- 
2.47.3