diff --git a/hw/nvram/chrp_nvram.c b/hw/nvram/chrp_nvram.c
index d969f267048e..d4d10a7c03c7 100644
--- a/hw/nvram/chrp_nvram.c
+++ b/hw/nvram/chrp_nvram.c
@@ -21,14 +21,21 @@
 
 #include "qemu/osdep.h"
 #include "qemu/cutils.h"
+#include "qemu/error-report.h"
 #include "hw/nvram/chrp_nvram.h"
 #include "sysemu/sysemu.h"
 
-static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str)
+static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str,
+                              int max_len)
 {
     int len;
 
     len = strlen(str) + 1;
+
+    if (max_len < len) {
+        return -1;
+    }
+
     memcpy(&nvram[addr], str, len);
 
     return addr + len;
@@ -38,19 +45,26 @@ static int chrp_nvram_set_var(uint8_t *nvram, int addr, const char *str)
  * Create a "system partition", used for the Open Firmware
  * environment variables.
  */
-int chrp_nvram_create_system_partition(uint8_t *data, int min_len)
+int chrp_nvram_create_system_partition(uint8_t *data, int min_len, int max_len)
 {
     ChrpNvramPartHdr *part_header;
     unsigned int i;
     int end;
 
+    if (max_len < sizeof(*part_header)) {
+        goto fail;
+    }
+
     part_header = (ChrpNvramPartHdr *)data;
     part_header->signature = CHRP_NVPART_SYSTEM;
     pstrcpy(part_header->name, sizeof(part_header->name), "system");
 
     end = sizeof(ChrpNvramPartHdr);
     for (i = 0; i < nb_prom_envs; i++) {
-        end = chrp_nvram_set_var(data, end, prom_envs[i]);
+        end = chrp_nvram_set_var(data, end, prom_envs[i], max_len - end);
+        if (end == -1) {
+            goto fail;
+        }
     }
 
     /* End marker */
@@ -65,6 +79,10 @@ int chrp_nvram_create_system_partition(uint8_t *data, int min_len)
     chrp_nvram_finish_partition(part_header, end);
 
     return end;
+
+fail:
+    error_report("NVRAM is too small. Try to pass less data to -prom-env");
+    exit(EXIT_FAILURE);
 }
 
 /**
diff --git a/hw/nvram/mac_nvram.c b/hw/nvram/mac_nvram.c
index beec1c4e4d11..11f2d31cdb20 100644
--- a/hw/nvram/mac_nvram.c
+++ b/hw/nvram/mac_nvram.c
@@ -141,7 +141,7 @@ static void pmac_format_nvram_partition_of(MacIONVRAMState *nvr, int off,
 
     /* OpenBIOS nvram variables partition */
     sysp_end = chrp_nvram_create_system_partition(&nvr->data[off],
-                                                  DEF_SYSTEM_SIZE) + off;
+                                                  DEF_SYSTEM_SIZE, len) + off;
 
     /* Free space partition */
     chrp_nvram_create_free_partition(&nvr->data[sysp_end], len - sysp_end);
diff --git a/hw/nvram/spapr_nvram.c b/hw/nvram/spapr_nvram.c
index 15d08281d411..386513499f59 100644
--- a/hw/nvram/spapr_nvram.c
+++ b/hw/nvram/spapr_nvram.c
@@ -188,7 +188,8 @@ static void spapr_nvram_realize(SpaprVioDevice *dev, Error **errp)
         }
     } else if (nb_prom_envs > 0) {
         /* Create a system partition to pass the -prom-env variables */
-        chrp_nvram_create_system_partition(nvram->buf, MIN_NVRAM_SIZE / 4);
+        chrp_nvram_create_system_partition(nvram->buf, MIN_NVRAM_SIZE / 4,
+                                           nvram->size);
         chrp_nvram_create_free_partition(&nvram->buf[MIN_NVRAM_SIZE / 4],
                                          nvram->size - MIN_NVRAM_SIZE / 4);
     }
diff --git a/hw/sparc/sun4m.c b/hw/sparc/sun4m.c
index 9be930415f8e..cf7dfa4af5de 100644
--- a/hw/sparc/sun4m.c
+++ b/hw/sparc/sun4m.c
@@ -143,7 +143,7 @@ static void nvram_init(Nvram *nvram, uint8_t *macaddr,
     memset(image, '\0', sizeof(image));
 
     /* OpenBIOS nvram variables partition */
-    sysp_end = chrp_nvram_create_system_partition(image, 0);
+    sysp_end = chrp_nvram_create_system_partition(image, 0, 0x1fd0);
 
     /* Free space partition */
     chrp_nvram_create_free_partition(&image[sysp_end], 0x1fd0 - sysp_end);
diff --git a/hw/sparc64/sun4u.c b/hw/sparc64/sun4u.c
index 9e30203dcc44..37310b73e6c2 100644
--- a/hw/sparc64/sun4u.c
+++ b/hw/sparc64/sun4u.c
@@ -136,7 +136,7 @@ static int sun4u_NVRAM_set_params(Nvram *nvram, uint16_t NVRAM_size,
     memset(image, '\0', sizeof(image));
 
     /* OpenBIOS nvram variables partition */
-    sysp_end = chrp_nvram_create_system_partition(image, 0);
+    sysp_end = chrp_nvram_create_system_partition(image, 0, 0x1fd0);
 
     /* Free space partition */
     chrp_nvram_create_free_partition(&image[sysp_end], 0x1fd0 - sysp_end);
diff --git a/include/hw/nvram/chrp_nvram.h b/include/hw/nvram/chrp_nvram.h
index 09941a9be454..4a0f5c21b884 100644
--- a/include/hw/nvram/chrp_nvram.h
+++ b/include/hw/nvram/chrp_nvram.h
@@ -50,7 +50,8 @@ chrp_nvram_finish_partition(ChrpNvramPartHdr *header, uint32_t size)
     header->checksum = sum & 0xff;
 }
 
-int chrp_nvram_create_system_partition(uint8_t *data, int min_len);
+/* chrp_nvram_create_system_partition() failure is fatal */
+int chrp_nvram_create_system_partition(uint8_t *data, int min_len, int max_len);
 int chrp_nvram_create_free_partition(uint8_t *data, int len);
 
 #endif
