linux-kernel - [PATCH 5/8] staging: wfx: increase robustness of hif_generic

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Message-Id: <20201009171307.864608-6-Jerome.Pouiller@silabs.com>
Date:   Fri,  9 Oct 2020 19:13:04 +0200
From:   Jerome Pouiller <Jerome.Pouiller@...abs.com>
To:     devel@...verdev.osuosl.org, linux-wireless@...r.kernel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S . Miller" <davem@...emloft.net>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Jérôme Pouiller 
        <jerome.pouiller@...abs.com>
Subject: [PATCH 5/8] staging: wfx: increase robustness of hif_generic_confirm()

From: Jérôme Pouiller <jerome.pouiller@...abs.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.carpenter@...cle.com>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@...abs.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