[PATCH] s390x: sthyi: Fix section size requirement and error

[Janosch Frank]

Some old z/VM instances report only 40 bytes for the partition
section, as they don't report the last three struct members.

Let's lower the size check of that section to 40 to accommodate them.

Also we expect a section to be at least x bytes, so we should make
that clear in the error message.

Signed-off-by: Janosch Frank <frankja at linux.ibm.com>
---
I already sent this out in Mach 2019, but it seems the patch got lost.
Old z/VM instances on z12 are still in our CI environment and this
problem breaks the tests on such machines.
---
 s390.c             | 26 ++++++++++++++------------
 tests/s390_sthyi.c | 30 +++++++++++++++---------------
 2 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/s390.c b/s390.c
index 54ece4b9..a02d1884 100644
--- a/s390.c
+++ b/s390.c
@@ -592,7 +592,7 @@ static void
 print_sthyi_partition(struct tcb *tcp, struct sthyi_partition *hdr,
 		      uint16_t size, bool *mt)
 {
-	size_t last_decoded = offsetofend(typeof(*hdr), infplgif);
+	size_t last_decoded = offsetofend(typeof(*hdr), infpabif);
 	int cnt_val, wcap_val, acap_val, id_val, lpar_val;
 
 	*mt = false;
@@ -662,18 +662,20 @@ print_sthyi_partition(struct tcb *tcp, struct sthyi_partition *hdr,
 		if (acap_val || hdr->infpabif)
 			PRINT_FIELD_WEIGHT(", ", *hdr, infpabif);
 
-		if (!IS_ARRAY_ZERO(hdr->infplgnm)) {
-			PRINT_FIELD_EBCDIC(", ", *hdr, infplgnm);
+		if (size >= offsetofend(struct sthyi_partition, infplgif)) {
+			if (!IS_ARRAY_ZERO(hdr->infplgnm)) {
+				PRINT_FIELD_EBCDIC(", ", *hdr, infplgnm);
 
-			PRINT_FIELD_WEIGHT(", ", *hdr, infplgcp);
-			PRINT_FIELD_WEIGHT(", ", *hdr, infplgif);
-		} else {
-			if (lpar_val)
-				PRINT_FIELD_HEX_ARRAY(", ", *hdr, infplgnm);
-			if (hdr->infplgcp)
-				PRINT_FIELD_X(", ", *hdr, infplgcp);
-			if (hdr->infplgif)
-				PRINT_FIELD_X(", ", *hdr, infplgif);
+				PRINT_FIELD_WEIGHT(", ", *hdr, infplgcp);
+				PRINT_FIELD_WEIGHT(", ", *hdr, infplgif);
+			} else {
+				if (lpar_val)
+					PRINT_FIELD_HEX_ARRAY(", ", *hdr, infplgnm);
+				if (hdr->infplgcp)
+					PRINT_FIELD_X(", ", *hdr, infplgcp);
+				if (hdr->infplgif)
+					PRINT_FIELD_X(", ", *hdr, infplgif);
+			}
 		}
 
 		if (size >= offsetofend(struct sthyi_partition, infpplnm)) {
diff --git a/tests/s390_sthyi.c b/tests/s390_sthyi.c
index 96c54d96..48c3dda7 100644
--- a/tests/s390_sthyi.c
+++ b/tests/s390_sthyi.c
@@ -509,7 +509,7 @@ print_sthyi(unsigned char *buf)
 	hdr_size = *(uint16_t *) (buf + 10);
 	if (hdr_size < 44)
 		error_msg_and_fail("sthyi: header section is too small "
-			           "(got %hu, 44 expected)", hdr_size);
+				   "(got %hu, >=44 expected)", hdr_size);
 
 	/* INFHFLG1 */
 	print_0x8("{/* header */ {infhflg1", buf, 0, true);
@@ -598,7 +598,7 @@ print_sthyi(unsigned char *buf)
 	hdr_size = *(uint16_t *) (buf + 14);
 	if (hdr_size < 60)
 		error_msg_and_fail("sthyi: machine section is too small "
-			           "(got %hu, 60 expected)", hdr_size);
+				   "(got %hu, >=60 expected)", hdr_size);
 
 	cur = buf + offs;
 
@@ -670,9 +670,9 @@ partition_hdr:
 		goto hv_hdr;
 
 	hdr_size = *(uint16_t *) (buf + 18);
-	if (hdr_size < 56)
+	if (hdr_size < 40)
 		error_msg_and_fail("sthyi: partition section is too small "
-			           "(got %hu, 56 expected)", hdr_size);
+				   "(got %hu, >=40 expected)", hdr_size);
 
 	cur = buf + offs;
 
@@ -741,18 +741,18 @@ partition_hdr:
 	print_weight(", infpwbif", cur, 32, pwcap_valid);
 	print_weight(", infpabif", cur, 36, pacap_valid);
 
-	if (print_ebcdic(", infplgnm", cur, 40, 8, false, false)) {
-
-		print_weight(", infplgcp", cur, 48, false);
-		print_weight(", infplgif", cur, 52, false);
-	} else {
-		if (lpar_valid) {
-			printf(", infplgnm=");
-			print_quoted_hex((char *) (cur + 40), 8);
+	if (hdr_size >= 56) {
+		if (print_ebcdic(", infplgnm", cur, 40, 8, false, false)) {
+			print_weight(", infplgcp", cur, 48, false);
+			print_weight(", infplgif", cur, 52, false);
+		} else {
+			if (lpar_valid) {
+				printf(", infplgnm=");
+				print_quoted_hex((char *) (cur + 40), 8);
+			}
+			print_x32(", infplgcp", cur, 48, false);
+			print_x32(", infplgif", cur, 52, false);
 		}
-
-		print_x32(", infplgcp", cur, 48, false);
-		print_x32(", infplgif", cur, 52, false);
 	}
 
 	if (hdr_size >= 64) {
-- 
2.25.1