[PATCH 3.16 016/306] zfcp: fix payload trace length for SAN request&response

Ben Hutchings
2017-02-15T23:19:15Z

From: Steffen Maier <maier@linux.vnet.ibm.com>

commit 94db3725f049ead24c96226df4a4fb375b880a77 upstream.

commit 2c55b750a884b86dea8b4cc5f15e1484cc47a25c
("[SCSI] zfcp: Redesign of the debug tracing for SAN records.")
started to add FC_CT_HDR_LEN which made zfcp dump random data
out of bounds for RSPN GS responses because u.rspn.rsp
is the largest and last field in the union of struct zfcp_fc_req.
Other request/response types only happened to stay within bounds
due to the padding of the union or
due to the trace capping of u.gspn.rsp to ZFCP_DBF_SAN_MAX_PAYLOAD.

Timestamp : ...
Area : SAN
Subarea : 00
Level : 1
Exception : -
CPU id : ..
Caller : ...
Record id : 2
Tag : fsscth2
Request id : 0x...
Destination ID : 0x00fffffc
Payload short : 01000000 fc020000 80020000 00000000
xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx <===
00000000 00000000 00000000 00000000
Payload length : 32 <===

struct zfcp_fc_req {
[0] struct zfcp_fsf_ct_els ct_els;
[56] struct scatterlist sg_req;
[96] struct scatterlist sg_rsp;
union {
struct {req; rsp;} adisc; SIZE: 28+28= 56
struct {req; rsp;} gid_pn; SIZE: 24+20= 44
struct {rspsg; req;} gpn_ft; SIZE: 40*4+20=180
struct {req; rsp;} gspn; SIZE: 20+273= 293
struct {req; rsp;} rspn; SIZE: 277+16= 293
[136] } u;
}
SIZE: 432

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Fixes: 2c55b750a884 ("[SCSI] zfcp: Redesign of the debug tracing for SAN records.")
Reviewed-by: Alexey Ishchuk <aishchuk@linux.vnet.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/s390/scsi/zfcp_dbf.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/s390/scsi/zfcp_dbf.c
+++ b/drivers/s390/scsi/zfcp_dbf.c
@@ -389,7 +389,7 @@ void zfcp_dbf_san_req(char *tag, struct
struct zfcp_fsf_ct_els *ct_els = fsf->data;
u16 length;

- length = (u16)(ct_els->req->length + FC_CT_HDR_LEN);
+ length = (u16)(ct_els->req->length);
zfcp_dbf_san(tag, dbf, sg_virt(ct_els->req), ZFCP_DBF_SAN_REQ, length,
fsf->req_id, d_id);
}
@@ -405,7 +405,7 @@ void zfcp_dbf_san_res(char *tag, struct
struct zfcp_fsf_ct_els *ct_els = fsf->data;
u16 length;

- length = (u16)(ct_els->resp->length + FC_CT_HDR_LEN);
+ length = (u16)(ct_els->resp->length);
zfcp_dbf_san(tag, dbf, sg_virt(ct_els->resp), ZFCP_DBF_SAN_RES, length,
fsf->req_id, ct_els->d_id);
}