[PATCH] Check sk before sendpage

[Yang Bin]

From: " Yang Bin "<yang....@zte.com.cn>

Before xmit,iscsi may disconnect just now.
So must check connection sock NULL or not,or kernel will crash for
accessing NULL pointer.

Signed-off-by: Yang Bin <yang....@zte.com.cn>
---
drivers/scsi/iscsi_tcp.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 7bedbe8..a59c49f 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -264,6 +264,9 @@ static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
unsigned int copied = 0;
int r = 0;

+ if (!sk)
+ return -ENOTCONN;
+
while (!iscsi_tcp_segment_done(tcp_conn, segment, 0, r)) {
struct scatterlist *sg;
unsigned int offset, copy;
--
1.8.3.1

[Lee Duncan]

If the socket can be closed right before iscsi_sw_tcp_xmit_segment() is
called, can it be called in the middle of sending segments? (In which
case the check would have to be in the while loop.)

--

Lee Duncan

[James Bottomley]

I think the important point is: is this an actual observed bug or just
a theoretical problem?

The reason for asking is this call is controlled directly by the
ISCSI_UEVENT_DESTROY_CONN event sent by the iscsi daemon. Obviously if
the daemon goes haywire and doesn't shut down the connection before
sending the destroy event, we may get the crash, but I would be
inclined to say fix the daemon.

James

[yang....@zte.com.cn]

> James
We have repproduced this bug several times .
It`s a good idea that sending ISCSI_UEVENT_STOP_CONN event first.
But there is another choice , adding "iscsi_suspend_tx" int the front of "destroy" ,
for not increasing dependence between kernel and daemon.

Yangbin