[stgt] [RESEND] [PATCH] Fix for segfault in tgtd sendtargets

[FUJITA Tomonori]

On Mon, 20 Apr 2009 16:21:01 +0200
Arne Redlich <arne.redlich at googlemail.com> wrote:

> Sorry for being that late in the game, but I think the patch should be
> reverted:
> 
> Am Freitag, den 03.04.2009, 00:45 +0100 schrieb Chris Webb: 
> > I have an amd64 host exporting around 70 iscsi targets (each with one LUN)
> > using tgtd. Exporting the targets works fine, but when I run a 'sendtargets'
> > discovery against the host, tgtd segfaults in conn_exit() because of heap
> > corruption when it tries to free conn->rsp_buffer.
> > 
> >   (gdb) print conn->rsp.datasize                 
> >   $12 = 13104
> > 
> > It turns out conn->rsp_buffer is being filled beyond INCOMING_BUFSIZE (8192)
> > by text_key_add() because it checks for overflow of conn->tx_size instead of
> > conn->rsp.datasize. The faulty test is fixed by:
> > 
> > Signed-off-by: Chris Webb <chris at arachsys.com>
> > 
> > diff -uNrp a/usr/iscsi/iscsid.c b/usr/iscsi/iscsid.c
> > --- a/usr/iscsi/iscsid.c	2009-03-28 22:54:21.000000000 +0000
> > +++ b/usr/iscsi/iscsid.c	2009-03-28 23:09:06.000000000 +0000
> > @@ -160,7 +160,7 @@ void text_key_add(struct iscsi_connectio
> >  	if (!conn->rsp.datasize)
> >  		conn->rsp.data = conn->rsp_buffer;
> >  
> > -	if (conn->tx_size + len > INCOMING_BUFSIZE) {
> > +	if (conn->rsp.datasize + len > INCOMING_BUFSIZE) {
> >  		log_warning("Dropping key (%s=%s)", key, value);
> >  		return;
> >  	}
> > 
> > 
> > However, I don't think this is the right fix, 
> 
> No, it actually is.

Duh, you are right. I'll revert the commit and put the above.


> > because sendtargets would
> > remain broken as soon as the size of the target list exceeed
> > INCOMING_BUFSIZE. The following patch instead realloc()s the response buffer
> > if it needs to grow to accommodate the target list:
> 
> The buffer cannot be arbitrarily reallocated. Ultimately this will lead
> to a violation of the MaxRecvDSL the initiator (implicitly) declared. To
> get this right the target list will have to be split into multiple PDUs,
> which is AFAIK not supported.

Yeah.

Hmm, I can't recall why we supports MaxRecvDSL negotiation in
discovery session.
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