[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>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/scsi/libfc/fc_lport.c b/drivers/scsi/libfc/fc_lport.c
index 0d19ffa8871..536492ae6a8 100644
--- a/drivers/scsi/libfc/fc_lport.c
+++ b/drivers/scsi/libfc/fc_lport.c
@@ -1115,7 +1115,7 @@ static void fc_lport_enter_scr(struct fc_lport *lport)
 
 	if (!lport->tt.elsct_send(lport, FC_FID_FCTRL, fp, ELS_SCR,
 				  fc_lport_scr_resp, lport, lport->e_d_tov))
-		fc_lport_error(lport, fp);
+		fc_lport_error(lport, NULL);
 }
 
 /**
@@ -1186,7 +1186,7 @@ static void fc_lport_enter_rpn_id(struct fc_lport *lport)
 	if (!lport->tt.elsct_send(lport, FC_FID_DIR_SERV, fp, FC_NS_RPN_ID,
 				  fc_lport_rpn_id_resp,
 				  lport, lport->e_d_tov))
-		fc_lport_error(lport, fp);
+		fc_lport_error(lport, NULL);
 }
 
 static struct fc_rport_operations fc_lport_rport_ops = {
@@ -1340,7 +1340,7 @@ static void fc_lport_enter_logo(struct fc_lport *lport)
 
 	if (!lport->tt.elsct_send(lport, FC_FID_FLOGI, fp, ELS_LOGO,
 				  fc_lport_logo_resp, lport, lport->e_d_tov))
-		fc_lport_error(lport, fp);
+		fc_lport_error(lport, NULL);
 }
 
 /**
@@ -1456,7 +1456,7 @@ void fc_lport_enter_flogi(struct fc_lport *lport)
 
 	if (!lport->tt.elsct_send(lport, FC_FID_FLOGI, fp, ELS_FLOGI,
 				  fc_lport_flogi_resp, lport, lport->e_d_tov))
-		fc_lport_error(lport, fp);
+		fc_lport_error(lport, NULL);
 }
 
 /* Configure a fc_lport */