linux/drivers/scsi/libfc/fc_elsct.c
Chris Leech 8f550f937e [SCSI] libfc: fix memory corruption caused by double frees and bad error handling
I was running into several different panics under stress, which I traced down
to a few different possible slab corruption issues in error handling paths.
I have not yet looked into why these exchange sends fail, but with these
fixes my test system is much more stable under stress than before.

fc_elsct_send() could fail and either leave the passed in frame intact
(failure in fc_ct/els_fill) or the frame could have been freed if the
failure was is fc_exch_seq_send().  The caller had no way of knowing, and
there was a potential double free in the error handling in fc_fcp_rec().

Make fc_elsct_send() always free the frame before returning, and remove the
fc_frame_free() call in fc_fcp_rec().

While fc_exch_seq_send() did always consume the frame, there were double free
bugs in the error handling of fc_fcp_cmd_send() and fc_fcp_srr() as well.

Numerous calls to error handling routines (fc_disc_error(),
fc_lport_error(), fc_rport_error_retry() ) were passing in a frame pointer that
had already been freed in the case of an error.  I have changed the call
sites to pass in a NULL pointer, but there may be more appropriate error
codes to use.

Question:  Why do these error routines take a frame pointer anyway?  I
understand passing in a pointer encoded error to the response handlers, but
the error routines take no action on a valid pointer and should never be
called that way.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2009-12-04 12:00:34 -06:00

113 lines
2.6 KiB
C

/*
* Copyright(c) 2008 Intel Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
* Maintained at www.Open-FCoE.org
*/
/*
* Provide interface to send ELS/CT FC frames
*/
#include <asm/unaligned.h>
#include <scsi/fc/fc_gs.h>
#include <scsi/fc/fc_ns.h>
#include <scsi/fc/fc_els.h>
#include <scsi/libfc.h>
#include <scsi/fc_encode.h>
/*
* fc_elsct_send - sends ELS/CT frame
*/
static struct fc_seq *fc_elsct_send(struct fc_lport *lport,
u32 did,
struct fc_frame *fp,
unsigned int op,
void (*resp)(struct fc_seq *,
struct fc_frame *fp,
void *arg),
void *arg, u32 timer_msec)
{
enum fc_rctl r_ctl;
enum fc_fh_type fh_type;
int rc;
/* ELS requests */
if ((op >= ELS_LS_RJT) && (op <= ELS_AUTH_ELS))
rc = fc_els_fill(lport, did, fp, op, &r_ctl, &fh_type);
else {
/* CT requests */
rc = fc_ct_fill(lport, did, fp, op, &r_ctl, &fh_type);
did = FC_FID_DIR_SERV;
}
if (rc) {
fc_frame_free(fp);
return NULL;
}
fc_fill_fc_hdr(fp, r_ctl, did, fc_host_port_id(lport->host), fh_type,
FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);
return lport->tt.exch_seq_send(lport, fp, resp, NULL, arg, timer_msec);
}
int fc_elsct_init(struct fc_lport *lport)
{
if (!lport->tt.elsct_send)
lport->tt.elsct_send = fc_elsct_send;
return 0;
}
EXPORT_SYMBOL(fc_elsct_init);
/**
* fc_els_resp_type() - return string describing ELS response for debug.
* @fp: frame pointer with possible error code.
*/
const char *fc_els_resp_type(struct fc_frame *fp)
{
const char *msg;
if (IS_ERR(fp)) {
switch (-PTR_ERR(fp)) {
case FC_NO_ERR:
msg = "response no error";
break;
case FC_EX_TIMEOUT:
msg = "response timeout";
break;
case FC_EX_CLOSED:
msg = "response closed";
break;
default:
msg = "response unknown error";
break;
}
} else {
switch (fc_frame_payload_op(fp)) {
case ELS_LS_ACC:
msg = "accept";
break;
case ELS_LS_RJT:
msg = "reject";
break;
default:
msg = "response unknown ELS";
break;
}
}
return msg;
}