From: Jérôme Pouiller <jerome.pouil...@silabs.com>

Smatch complains:

    drivers/staging/wfx/hif_rx.c:26 hif_generic_confirm() warn: negative user 
subtract: 0-u16max - 4
    20  static int hif_generic_confirm(struct wfx_dev *wdev,
    21                                 const struct hif_msg *hif, const void 
*buf)
    22  {
    23          // All confirm messages start with status
    24          int status = le32_to_cpup((__le32 *)buf);
    25          int cmd = hif->id;
    26          int len = le16_to_cpu(hif->len) - 4; // drop header
                                              ^^^^^
    27
    28          WARN(!mutex_is_locked(&wdev->hif_cmd.lock), "data locking 
error");

In fact, rx_helper() already make the necessary checks on the value of
hif->len. Never mind, add an explicit check to make Smatch happy.

Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouil...@silabs.com>
---
 drivers/staging/wfx/hif_rx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/wfx/hif_rx.c b/drivers/staging/wfx/hif_rx.c
index ca09467cba05..2d4265257112 100644
--- a/drivers/staging/wfx/hif_rx.c
+++ b/drivers/staging/wfx/hif_rx.c
@@ -40,10 +40,10 @@ static int hif_generic_confirm(struct wfx_dev *wdev,
        }
 
        if (wdev->hif_cmd.buf_recv) {
-               if (wdev->hif_cmd.len_recv >= len)
+               if (wdev->hif_cmd.len_recv >= len && len > 0)
                        memcpy(wdev->hif_cmd.buf_recv, buf, len);
                else
-                       status = -ENOMEM;
+                       status = -EIO;
        }
        wdev->hif_cmd.ret = status;
 
-- 
2.28.0

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