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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Pietro Oliva <pietroliva@gmail.com>,
        Larry Finger <Larry.Finger@lwfinger.net>
Subject: [PATCH 4.19 34/97] staging: rtl8723bs: Fix potential overuse of kernel memory
Date:   Thu, 27 Feb 2020 14:36:42 +0100
Message-Id: <20200227132220.151023016@linuxfoundation.org>
In-Reply-To: <20200227132214.553656188@linuxfoundation.org>
References: <20200227132214.553656188@linuxfoundation.org>
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From: Larry Finger <Larry.Finger@lwfinger.net>

commit 23954cb078febfc63a755301fe77e06bccdb4d2a upstream.

In routine wpa_supplicant_ioctl(), the user-controlled p->length is
checked to be at least the size of struct ieee_param size, but the code
does not detect the case where p->length is greater than the size
of the struct, thus a malicious user could be wasting kernel memory.
Fixes commit 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver").

Reported by: Pietro Oliva <pietroliva@gmail.com>
Cc: Pietro Oliva <pietroliva@gmail.com>
Cc: Stable <stable@vger.kernel.org>
Fixes: 554c0a3abf216 ("staging: Add rtl8723bs sdio wifi driver").
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Link: https://lore.kernel.org/r/20200210180235.21691-5-Larry.Finger@lwfinger.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/rtl8723bs/os_dep/ioctl_linux.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_linux.c
@@ -3400,7 +3400,7 @@ static int wpa_supplicant_ioctl(struct n
 
 	/* down(&ieee->wx_sem); */
 
-	if (p->length < sizeof(struct ieee_param) || !p->pointer) {
+	if (!p->pointer || p->length != sizeof(struct ieee_param)) {
 		ret = -EINVAL;
 		goto out;
 	}