[PATCH 09/12] kvm-all: introduce limits for name_size and num_desc

[Vladimir Sementsov-Ogievskiy]

Coverity doesn't like when the value with unchecked bounds that comes
from fd is used as length for IO or allocation. And really, that's not
a good practice. Let's introduce at least an empirical limits for these
values.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
 accel/kvm/kvm-all.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index ff1578bb32..6d0ba7d900 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3988,6 +3988,9 @@ typedef struct StatsDescriptors {
 static QTAILQ_HEAD(, StatsDescriptors) stats_descriptors =
     QTAILQ_HEAD_INITIALIZER(stats_descriptors);
 
+
+#define KVM_STATS_QEMU_MAX_NAME_SIZE (1024 * 1024)
+#define KVM_STATS_QEMU_MAX_NUM_DESC (1024)
 /*
  * Return the descriptors for 'target', that either have already been read
  * or are retrieved from 'stats_fd'.
@@ -4021,6 +4024,18 @@ static StatsDescriptors 
*find_stats_descriptors(StatsTarget target, int stats_fd
         g_free(descriptors);
         return NULL;
     }
+    if (kvm_stats_header->name_size > KVM_STATS_QEMU_MAX_NAME_SIZE) {
+        error_setg(errp, "KVM stats: too large name_size: %" PRIu32,
+                   kvm_stats_header->name_size);
+        g_free(descriptors);
+        return NULL;
+    }
+    if (kvm_stats_header->num_desc > KVM_STATS_QEMU_MAX_NUM_DESC) {
+        error_setg(errp, "KVM stats: too large num_desc: %" PRIu32,
+                   kvm_stats_header->num_desc);
+        g_free(descriptors);
+        return NULL;
+    }
     size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
 
     /* Read stats descriptors */
-- 
2.34.1