[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, 1 insertions, 1 deletions

diff --git a/drivers/scsi/libfc/fc_disc.c b/drivers/scsi/libfc/fc_disc.c
index c48799e..d4cb3f9 100644
--- a/drivers/scsi/libfc/fc_disc.c
+++ b/drivers/scsi/libfc/fc_disc.c
@@ -371,7 +371,7 @@ static void fc_disc_gpn_ft_req(struct fc_disc *disc)
 				 disc, lport->e_d_tov))
 		return;
 err:
-	fc_disc_error(disc, fp);
+	fc_disc_error(disc, NULL);
 }
 
 /**