linux-kernel - [PATCH] staging: r8188eu: fix -Wrestrict warnings

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Message-Id: <20210920095525.1150678-1-arnd@kernel.org>
Date:   Mon, 20 Sep 2021 11:55:09 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Michael Straube <straube.linux@...il.com>,
        Martin Kaiser <martin@...ser.cx>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: r8188eu: fix -Wrestrict warnings

From: Arnd Bergmann <arnd@...db.de>

Adding back the nonstandard ioctl commands caused -Wrestrict warnings
when building with 'make W=1':

drivers/staging/r8188eu/os_dep/ioctl_linux.c: In function 'rtw_mp_read_rf':
drivers/staging/r8188eu/os_dep/ioctl_linux.c:5515:27: error: 'sprintf' argument 3 overlaps destination object 'extra' [-Werror=restrict]
 5515 |                           sprintf(extra, "%s %d", extra, strtou);
      |                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/staging/r8188eu/os_dep/ioctl_linux.c:5470:54: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
 5470 |                         struct iw_point *wrqu, char *extra)
      |                                                ~~~~~~^~~~~

Change these to the same construct used elsewhere in that driver,
with an offset to the string to make the warning go away.

The ioctl commands were previously removed, and it's unlikely that
anything is actually using them, so ideally I would prefer to have
them removed again.

The lack of range checking of the 'extra' output buffer is also
slightly worrying, but I did not check whether this could cause
harm.

Fixes: 2b42bd58b321 ("staging: r8188eu: introduce new os_dep dir for RTL8188eu driver")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/staging/r8188eu/os_dep/ioctl_linux.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/r8188eu/os_dep/ioctl_linux.c b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
index 81d4255d1785..1fd375076001 100644
--- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
+++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
@@ -5372,8 +5372,8 @@ static int rtw_mp_read_reg(struct net_device *dev,
 
 			pnext++;
 			if (*pnext != '\0') {
-				  strtout = simple_strtoul(pnext, &ptmp, 16);
-				  sprintf(extra, "%s %d", extra, strtout);
+				strtout = simple_strtoul(pnext, &ptmp, 16);
+				sprintf(extra + strlen(extra), " %d", strtout);
 			} else {
 				  break;
 			}
@@ -5405,7 +5405,7 @@ static int rtw_mp_read_reg(struct net_device *dev,
 			pnext++;
 			if (*pnext != '\0') {
 				strtout = simple_strtoul(pnext, &ptmp, 16);
-				sprintf(extra, "%s %d", extra, strtout);
+				sprintf(extra + strlen(extra), " %d", strtout);
 			} else {
 				break;
 			}
@@ -5512,7 +5512,7 @@ static int rtw_mp_read_rf(struct net_device *dev,
 		pnext++;
 		if (*pnext != '\0') {
 			  strtou = simple_strtoul(pnext, &ptmp, 16);
-			  sprintf(extra, "%s %d", extra, strtou);
+			  sprintf(extra + strlen(extra), " %d", strtou);
 		} else {
 			  break;
 		}
-- 
2.29.2