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From: Haggai Eran <haggai.eran@gmail.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: linux-wireless@vger.kernel.org, Haggai Eran <haggai.eran@gmail.com>
Subject: [PATCH] staging: rtl8712: prevent buffer overrun in recvbuf2recvframe
Date: Tue, 19 May 2015 08:47:24 +0300
Message-Id: <1432014444-29039-1-git-send-email-haggai.eran@gmail.com>

With an RTL8191SU USB adaptor, sometimes the hints for a fragmented
packet are set, but the packet length is too large. Truncate the packet
to prevent memory corruption.

Signed-off-by: Haggai Eran <haggai.eran@gmail.com>
---

Hi,

I think this solves the issue for me. I'll test it more thoroughly later. I
still don't know why a fragmented packet has such a large pkt_len value though. 

Thanks,
Haggai

 drivers/staging/rtl8712/rtl8712_recv.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Index: wireless-drivers-next/drivers/staging/rtl8712/rtl8712_recv.c
===================================================================
--- wireless-drivers-next.orig/drivers/staging/rtl8712/rtl8712_recv.c
+++ wireless-drivers-next/drivers/staging/rtl8712/rtl8712_recv.c
@@ -1053,12 +1053,7 @@ static int recvbuf2recvframe(struct _ada
 		precvframe->u.hdr.len = 0;
 		tmp_len = pkt_len + drvinfo_sz + RXDESC_SIZE;
 		pkt_offset = (u16)round_up(tmp_len, 128);
-		/* for first fragment packet, driver need allocate 1536 +
-		 * drvinfo_sz + RXDESC_SIZE to defrag packet. */
-		if ((mf == 1) && (frag == 0))
-			alloc_sz = 1658;/*1658+6=1664, 1664 is 128 alignment.*/
-		else
-			alloc_sz = tmp_len;
+		alloc_sz = tmp_len;
 		/* 2 is for IP header 4 bytes alignment in QoS packet case.
 		 * 4 is for skb->data 4 bytes alignment. */
 		alloc_sz += 6;