s390x: sthyi: Fix section size requirement and error

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@linux.ibm.com>
Reviewed-by: Eugene Syromyatnikov <evgsyr@gmail.com>

2 files changed, 30 insertions, 28 deletions

diff --git a/s390.c b/s390.c
index 54ece4b98..a02d1884a 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);
-
-			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, 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);
+			}
 		}
 
 		if (size >= offsetofend(struct sthyi_partition, infpplnm)) {
diff --git a/tests/s390_sthyi.c b/tests/s390_sthyi.c
index 96c54d967..48c3dda79 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) {