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From:   gregkh@linuxfoundation.org
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>
Subject: [PATCH 4.19 091/120] staging: rtl8712: unterminated string leads to read overflow
Date:   Mon, 15 Mar 2021 14:57:22 +0100
Message-Id: <20210315135722.957836292@linuxfoundation.org>
In-Reply-To: <20210315135720.002213995@linuxfoundation.org>
References: <20210315135720.002213995@linuxfoundation.org>
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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

From: Dan Carpenter <dan.carpenter@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 <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YDYSR+1rj26NRhvb@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@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
@@ -946,7 +946,7 @@ 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);