[PULL 12/37] hw/s390x: Define finite size for single entry VCEntry

[Eric Farman <farman@linux.ibm.com>]

From: Zhuoying Cai <zycai@linux.ibm.com>

Define MAX_VCENTRY_SIZE(8KB) and CERT_BUF_MAX_LEN to establish a finite
size for a single entry VCEntry. Add validation in update_cert_store()
to ensure certificate data does not exceed this limit.

This finite size definition is needed for proper memory allocation and
will be used in a later commit to handle VCEntry structures with known
size constraints.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260730214624.2328883-11-zycai@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 hw/s390x/cert-store.c          | 6 ++++++
 include/hw/s390x/ipl/diag320.h | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/hw/s390x/cert-store.c b/hw/s390x/cert-store.c
index c679406c2c..c086e75f75 100644
--- a/hw/s390x/cert-store.c
+++ b/hw/s390x/cert-store.c
@@ -91,6 +91,12 @@ static int update_cert_store(S390IPLCertificateStore *cert_store,
     cert_buf_size = ROUND_UP(cert->der_size, 4);
     data_buf_size = keyid_buf_size + hash_buf_size + cert_buf_size;
 
+    if (data_buf_size > CERT_BUF_MAX_LEN) {
+        error_report("Certificate data size %zu exceeds maximum buffer size %zu",
+                     data_buf_size, CERT_BUF_MAX_LEN);
+        return -1;
+    }
+
     if (cert_store->largest_cert_size < data_buf_size) {
         cert_store->largest_cert_size = data_buf_size;
     }
diff --git a/include/hw/s390x/ipl/diag320.h b/include/hw/s390x/ipl/diag320.h
index 7fda2d44fd..f3c23a3176 100644
--- a/include/hw/s390x/ipl/diag320.h
+++ b/include/hw/s390x/ipl/diag320.h
@@ -92,6 +92,9 @@ struct VCEntry {
 };
 typedef struct VCEntry VCEntry;
 
+#define MAX_VCENTRY_SIZE      (8 * 1024)
+#define CERT_BUF_MAX_LEN      (MAX_VCENTRY_SIZE - sizeof(VCEntryHeader))
+
 struct VCBlockHeader {
     uint32_t in_len;
     uint32_t reserved0;
-- 
2.55.0