[S390] dasd: fix idaw boundary checking for track based ccw

A ccw command that reads or writes several records at once will
usually transfer more data then fits into one page and needs to
address memory areas using a list of indirect data address words
(idaw). All but the first of these areas must start on a 4KB or 2KB
block boundary (depending on the idaw format).
A check for this restriction was missing and has been added with
this patch.

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 21254793c604..cb52da033f06 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -2019,15 +2019,23 @@ static struct dasd_ccw_req *dasd_eckd_build_cp_cmd_track(
                                 ccw++;
                                 recid += count;
                                 new_track = 0;
+                                /* first idaw for a ccw may start anywhere */
+                                if (!idaw_dst)
+                                        idaw_dst = dst;
                         }
-                        /* If we start a new idaw, everything is fine and the
-                         * start of the new idaw is the start of this segment.
+                        /* If we start a new idaw, we must make sure that it
+                         * starts on an IDA_BLOCK_SIZE boundary.
                          * If we continue an idaw, we must make sure that the
                          * current segment begins where the so far accumulated
                          * idaw ends
                          */
-                        if (!idaw_dst)
-                                idaw_dst = dst;
+                        if (!idaw_dst) {
+                                if (__pa(dst) & (IDA_BLOCK_SIZE-1)) {
+                                        dasd_sfree_request(cqr, startdev);
+                                        return ERR_PTR(-ERANGE);
+                                } else
+                                        idaw_dst = dst;
+                        }
                         if ((idaw_dst + idaw_len) != dst) {
                                 dasd_sfree_request(cqr, startdev);
                                 return ERR_PTR(-ERANGE);