linux-kernel - static analysis bug report: staging r8712u memcpy of uninitialized variable

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Message-ID: <2b54dc2d-7509-dc76-b730-4c8d66f81226@canonical.com>
Date:   Mon, 18 Mar 2019 11:20:51 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     Larry Finger <Larry.Finger@...inger.net>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>
Subject: static analysis bug report: staging r8712u memcpy of uninitialized
 variable

Hi,

Static analysis with cppcheck found a couple of interesting issues with
memcpy'ing of an uninitialized variable. Two occurrences of the same
issue are found in drivers/staging/rtl8712/rtl8712_cmd.c in functions
read_bbreg_hdl and read_rfreg_hdl.

For example:

static u8 read_bbreg_hdl(struct _adapter *padapter, u8 *pbuf)
{
        u32 val;
        void (*pcmd_callback)(struct _adapter *dev, struct cmd_obj
*pcmd);
        struct cmd_obj *pcmd  = (struct cmd_obj *)pbuf;

        if (pcmd->rsp && pcmd->rspsz > 0)
                memcpy(pcmd->rsp, (u8 *)&val, pcmd->rspsz);

	....

}

I don't understand why the contents of val is being memcpy'd to
pcmd->rsp, especially when val is uninitialized and hence contains
garbage. Any ideas?

Colin