[PATCH v6] staging: rtl8723bs: Add error handling for sd_read()

[Wentao Liang <vulab@iscas.ac.cn>]

The sdio_read32() calls sd_read(), but does not handle the error if
sd_read() fails. This could lead to subsequent operations processing
invalid data. A proper implementation can be found in sdio_readN().

Add error handling for the sd_read() to free tmpbuf and return error
code if sd_read() fails. This ensure that the memcpy() is only performed
when the read operation is successful.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
v6: Fix improper code to propagate error code
v5: Fix error code
v4: Add change log and fix error code
v3: Add Cc flag
v2: Change code to initialize val

 drivers/staging/rtl8723bs/hal/sdio_ops.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/hal/sdio_ops.c b/drivers/staging/rtl8723bs/hal/sdio_ops.c
index 21e9f1858745..eb21c7e55949 100644
--- a/drivers/staging/rtl8723bs/hal/sdio_ops.c
+++ b/drivers/staging/rtl8723bs/hal/sdio_ops.c
@@ -185,7 +185,12 @@ static u32 sdio_read32(struct intf_hdl *intfhdl, u32 addr)
 			return SDIO_ERR_VAL32;
 
 		ftaddr &= ~(u16)0x3;
-		sd_read(intfhdl, ftaddr, 8, tmpbuf);
+		err = sd_read(intfhdl, ftaddr, 8, tmpbuf);
+		if (err) {
+			kfree(tmpbuf);
+			return (u32)err;
+		}
+
 		memcpy(&le_tmp, tmpbuf + shift, 4);
 		val = le32_to_cpu(le_tmp);
 
-- 
2.42.0.windows.2