[PATCH 2/2] spapr/nvram: Allocate enough space for all -prom-env options

[Greg Kurz]

Since commit 61f20b9dc5b7 ("spapr_nvram: Pre-initialize the NVRAM to
support the -prom-env parameter"), pseries machines can pre-initialize
the "system" partition in the NVRAM with the data passed to all -prom-env
parameters on the QEMU command line.

In this cases it is assumed that all the data fits in 64 KiB, but the user
can easily pass more and crash QEMU:

$ qemu-system-ppc64 -M pseries $(for ((x=0;x<128;x++)); do \
  echo -n " -prom-env "$(for ((y=0;y<1024;y++)); do echo -n x ; done) ; \
  done) # this requires ~128 Kib
malloc(): corrupted top size
Aborted (core dumped)

Call chrp_nvram_create_system_partition() first with its recently added
parameter dry_run set to false, to know the required size and allocate
the NVRAM buffer accordingly.

Fixes: 61f20b9dc5b7 ("spapr_nvram: Pre-initialize the NVRAM to support the 
-prom-env parameter")
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/nvram/spapr_nvram.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/nvram/spapr_nvram.c b/hw/nvram/spapr_nvram.c
index 992b818d34e7..1b74bec6200a 100644
--- a/hw/nvram/spapr_nvram.c
+++ b/hw/nvram/spapr_nvram.c
@@ -165,6 +165,10 @@ static void spapr_nvram_realize(SpaprVioDevice *dev, Error 
**errp)
         if (ret < 0) {
             return;
         }
+    } else if (nb_prom_envs > 0) {
+        nvram->size = chrp_nvram_create_system_partition(NULL,
+                                                         MIN_NVRAM_SIZE / 4,
+                                                         true);
     } else {
         nvram->size = DEFAULT_NVRAM_SIZE;
     }