kvm: fix memory leak on failure to read stats descriptors

Reported by Coverity as CID 1490142.  Since the size is constant and the
lifetime is the same as the StatsDescriptors struct, embed the struct
directly instead of using a separate allocation.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 7c8ce18bdd22e1eccc93b7d78b4b799303d3f4ad..5acab1767fe1abc3f291a5ecf3b1d09ea5f5d907 100644 (file)
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3908,7 +3908,7 @@ exit:
 typedef struct StatsDescriptors {
     const char *ident; /* cache key, currently the StatsTarget */
     struct kvm_stats_desc *kvm_stats_desc;
-    struct kvm_stats_header *kvm_stats_header;
+    struct kvm_stats_header kvm_stats_header;
     QTAILQ_ENTRY(StatsDescriptors) next;
 } StatsDescriptors;
 
@@ -3939,7 +3939,7 @@ static StatsDescriptors *find_stats_descriptors(StatsTarget target, int stats_fd
     descriptors = g_new0(StatsDescriptors, 1);
 
     /* Read stats header */
-    kvm_stats_header = g_malloc(sizeof(*kvm_stats_header));
+    kvm_stats_header = &descriptors->kvm_stats_header;
     ret = read(stats_fd, kvm_stats_header, sizeof(*kvm_stats_header));
     if (ret != sizeof(*kvm_stats_header)) {
         error_setg(errp, "KVM stats: failed to read stats header: "
@@ -3964,7 +3964,6 @@ static StatsDescriptors *find_stats_descriptors(StatsTarget target, int stats_fd
         g_free(kvm_stats_desc);
         return NULL;
     }
-    descriptors->kvm_stats_header = kvm_stats_header;
     descriptors->kvm_stats_desc = kvm_stats_desc;
     descriptors->ident = ident;
     QTAILQ_INSERT_TAIL(&stats_descriptors, descriptors, next);
@@ -3989,7 +3988,7 @@ static void query_stats(StatsResultList **result, StatsTarget target,
         return;
     }
 
-    kvm_stats_header = descriptors->kvm_stats_header;
+    kvm_stats_header = &descriptors->kvm_stats_header;
     kvm_stats_desc = descriptors->kvm_stats_desc;
     size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
 
@@ -4054,7 +4053,7 @@ static void query_stats_schema(StatsSchemaList **result, StatsTarget target,
         return;
     }
 
-    kvm_stats_header = descriptors->kvm_stats_header;
+    kvm_stats_header = &descriptors->kvm_stats_header;
     kvm_stats_desc = descriptors->kvm_stats_desc;
     size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;