[PATCH 5.11 223/306] staging: rtl8712: unterminated string leads to read overflow

[gregkh]

From: Greg Kroah-Hartman <gre...@linuxfoundation.org>

From: Dan Carpenter <dan.carpen...@oracle.com>

commit d660f4f42ccea50262c6ee90c8e7ad19a69fb225 upstream.

The memdup_user() function does not necessarily return a NUL terminated
string so this can lead to a read overflow.  Switch from memdup_user()
to strndup_user() to fix this bug.

Fixes: c6dc001f2add ("staging: r8712u: Merging Realtek's latest (v2.6.6). 
Various fixes.")
Cc: stable <sta...@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
Link: https://lore.kernel.org/r/YDYSR+1rj26NRhvb@mwanda
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/staging/rtl8712/rtl871x_ioctl_linux.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c
+++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c
@@ -924,7 +924,7 @@ static int r871x_wx_set_priv(struct net_
        struct iw_point *dwrq = (struct iw_point *)awrq;
 
        len = dwrq->length;
-       ext = memdup_user(dwrq->pointer, len);
+       ext = strndup_user(dwrq->pointer, len);
        if (IS_ERR(ext))
                return PTR_ERR(ext);