scsi: sg: don't return bogus Sg_requests

commit 48ae8484e9fc324b4968d33c585e54bc98e44d61 upstream.

If the list search in sg_get_rq_mark() fails to find a valid request, we
return a bogus element. This then can later lead to a GPF in
sg_remove_scat().

So don't return bogus Sg_requests in sg_get_rq_mark() but NULL in case
the list search doesn't find a valid request.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Doug Gilbert <dgilbert@interlog.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Doug Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 7592ac8..f61b371 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -2064,11 +2064,12 @@ sg_get_rq_mark(Sg_fd * sfp, int pack_id)
                if ((1 == resp->done) && (!resp->sg_io_owned) &&
                    ((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
                        resp->done = 2; /* guard against other readers */
-                       break;
+                       write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+                       return resp;
                }
        }
        write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
-       return resp;
+       return NULL;
 }
 
 /* always adds to end of list */