This bug causes the wrong command to have its sense pointer overwritten,
which sometimes leads to a NULL pointer deref. Fix this by checking which
command is being requeued before restoring the scsi_eh_save data.
It turns out that some targets will disconnect a REQUEST SENSE command.
The autosense algorithm doesn't anticipate this. Hence multiple commands
can end up undergoing autosense simultaneously, and they will all try to
use the same scsi_eh_save struct, which won't work. Defer autosense when
the scsi_eh_save storage is in use by another command.
Fixes: f27db8eb98a1 ("ncr5380: Fix autosense bugs")
Reported-and-tested-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
---
drivers/scsi/NCR5380.c | 4 ++--
drivers/scsi/atari_NCR5380.c | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
Index: linux/drivers/scsi/NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/NCR5380.c 2016-02-23 10:07:01.000000000 +1100
+++ linux/drivers/scsi/NCR5380.c 2016-02-23 10:07:02.000000000 +1100
@@ -760,7 +760,7 @@ static struct scsi_cmnd *dequeue_next_cm
struct NCR5380_cmd *ncmd;
struct scsi_cmnd *cmd;
- if (list_empty(&hostdata->autosense)) {
+ if (hostdata->sensing || list_empty(&hostdata->autosense)) {
list_for_each_entry(ncmd, &hostdata->unissued, list) {
cmd = NCR5380_to_scmd(ncmd);
dsprintk(NDEBUG_QUEUES, instance, "dequeue: cmd=%p target=%d busy=0x%02x lun=%llu\n",
@@ -793,7 +793,7 @@ static void requeue_cmd(struct Scsi_Host
struct NCR5380_hostdata *hostdata = shost_priv(instance);
struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
- if (hostdata->sensing) {
+ if (hostdata->sensing == cmd) {
scsi_eh_restore_cmnd(cmd, &hostdata->ses);
list_add(&ncmd->list, &hostdata->autosense);
hostdata->sensing = NULL;
Index: linux/drivers/scsi/atari_NCR5380.c
===================================================================
--- linux.orig/drivers/scsi/atari_NCR5380.c 2016-02-23 10:07:01.000000000 +1100
+++ linux/drivers/scsi/atari_NCR5380.c 2016-02-23 10:07:02.000000000 +1100
@@ -862,7 +862,7 @@ static struct scsi_cmnd *dequeue_next_cm
struct NCR5380_cmd *ncmd;
struct scsi_cmnd *cmd;
- if (list_empty(&hostdata->autosense)) {
+ if (hostdata->sensing || list_empty(&hostdata->autosense)) {
list_for_each_entry(ncmd, &hostdata->unissued, list) {
cmd = NCR5380_to_scmd(ncmd);
dsprintk(NDEBUG_QUEUES, instance, "dequeue: cmd=%p target=%d busy=0x%02x lun=%llu\n",
@@ -901,7 +901,7 @@ static void requeue_cmd(struct Scsi_Host
struct NCR5380_hostdata *hostdata = shost_priv(instance);
struct NCR5380_cmd *ncmd = scsi_cmd_priv(cmd);
- if (hostdata->sensing) {
+ if (hostdata->sensing == cmd) {
scsi_eh_restore_cmnd(cmd, &hostdata->ses);
list_add(&ncmd->list, &hostdata->autosense);
hostdata->sensing = NULL;
--
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