Re:[PATCH] Check sk before sendpage
> On Wed, 2019-07-10 at 17:47 +, Lee Duncan wrote:
> > On 7/10/19 12:30 AM, Yang Bin wrote:
> >
> > > From: " Yang Bin "
> > >
> > > 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
> > > ---
> > > 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;
> > >
> >
> > 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.)
> 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
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
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Re: [PATCH] Check sk before sendpage
On Wed, 2019-07-10 at 17:47 +, Lee Duncan wrote:
> On 7/10/19 12:30 AM, Yang Bin wrote:
>
> > From: " Yang Bin "
> >
> > 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
> > ---
> > 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;
> >
>
> 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.)
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
Re: [PATCH] Check sk before sendpage
On 7/10/19 12:30 AM, Yang Bin wrote:
> From: " Yang Bin "
>
> 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
> ---
> 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;
>
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
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