USB: serial: mos7720: improve OOM-handling in read_mos_reg()
clang static analysis reports this problem
mos7720.c:352:2: warning: Undefined or garbage value returned to caller
return d;
^~~~~~~~
In the parport_mos7715_read_data()'s call to read_mos_reg(), 'd' is
only set after the alloc block.
buf = kmalloc(1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
Although the problem is reported in parport_most7715_read_data(),
none of the callee's of read_mos_reg() check the return status.
Make sure to clear the return-value buffer also on allocation failures.
Fixes: 0d130367abf5 ("USB: serial: mos7720: fix control-message error handling")
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20210111220904.1035957-1-trix@redhat.com
[ johan: only clear the buffer on errors, amend commit message ]
Signed-off-by: Johan Hovold <johan@kernel.org>
diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 41ee298..ed347a6 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -215,8 +215,10 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
int status;
buf = kmalloc(1, GFP_KERNEL);
- if (!buf)
+ if (!buf) {
+ *data = 0;
return -ENOMEM;
+ }
status = usb_control_msg(usbdev, pipe, request, requesttype, value,
index, buf, 1, MOS_WDR_TIMEOUT);
