[PATCH 14/20] libfc: Fix frags in frame exceeding SKB_MAX_FRAGS in fc_fcp_send_data

Robert Love
2009-10-21T23:28:10Z

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

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@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
---

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

diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 40ed744..28bfe1c 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -574,7 +574,8 @@ static int fc_fcp_send_data(struct fc_fcp_pkt *fsp, struct fc_seq *seq,
tlen -= sg_bytes;
remaining -= sg_bytes;

- if (tlen)
+ if ((skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN) &&
+ (tlen))
continue;

/*
diff --git a/include/scsi/fc_frame.h b/include/scsi/fc_frame.h
index c35d238..148126d 100644
--- 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)