linux-kernel - [48/98] [SCSI] libfc: Fix frags in frame exceeding SKB_MAX_FRAGS in fc_fcp_send

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Message-Id: <20100126233927.195499266@mini.kroah.org>
Date:	Tue, 26 Jan 2010 15:34:14 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Yi Zou <yi.zou@...el.com>,
	Robert Love <robert.w.love@...el.com>,
	James Bottomley <James.Bottomley@...e.de>
Subject: [48/98] [SCSI] libfc: Fix frags in frame exceeding SKB_MAX_FRAGS in fc_fcp_send_data

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Yi Zou <yi.zou@...el.com>

commit d37322a43ebac79eef417149f5696390cf8872db upstream.

In case of sequence offload, in fc_fcp_send_data(), the skb_fill_page_info()
called may end up adding more frags to the skb_shinfo(fp_skb(fp))->frags[],
exceeding SKB_MAX_FRAGS, this eventually corrupts the memory. I am adding the
FR_FRAME_SG_LEN back, but as SKB_MAX_FRAGS -1, leaving 1 for our fcoe_eof_crc
page. And send will be broken into multiple large sends if the frame already
contains more frags than skb handle.

Signed-off-by: Yi Zou <yi.zou@...el.com>
Signed-off-by: Robert Love <robert.w.love@...el.com>
Signed-off-by: James Bottomley <James.Bottomley@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/scsi/libfc/fc_fcp.c |    3 ++-
 include/scsi/fc_frame.h     |    3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -575,7 +575,8 @@ static int fc_fcp_send_data(struct fc_fc
 		tlen -= sg_bytes;
 		remaining -= sg_bytes;
 
-		if (tlen)
+		if ((skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN) &&
+		    (tlen))
 			continue;
 
 		/*
--- a/include/scsi/fc_frame.h
+++ b/include/scsi/fc_frame.h
@@ -37,6 +37,9 @@
 #define	FC_FRAME_HEADROOM	32	/* headroom for VLAN + FCoE headers */
 #define	FC_FRAME_TAILROOM	8	/* trailer space for FCoE */
 
+/* Max number of skb frags allowed, reserving one for fcoe_crc_eof page */
+#define FC_FRAME_SG_LEN		(MAX_SKB_FRAGS - 1)
+
 #define fp_skb(fp)	(&((fp)->skb))
 #define fr_hdr(fp)	((fp)->skb.data)
 #define fr_len(fp)	((fp)->skb.len)


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