linux-user: Allocate thunk size dynamically

We store all struct types in an array of static size without ever
checking whether we overrun it. Of course some day someone (like me
in another, ancient ALSA enabling patch set) will run into the limit
without realizing it.

So let's make the allocation dynamic. We already know the number of
structs that we want to allocate, so we only need to pass the variable
into the respective piece of code.

Also, to ensure we don't accidently overwrite random memory, add some
asserts to sanity check whether a thunk is actually part of our array.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/thunk.c b/thunk.c
index 3cca047509..f501fd72fc 100644
--- a/thunk.c
+++ b/thunk.c
@@ -25,10 +25,8 @@
 
 //#define DEBUG
 
-#define MAX_STRUCTS 128
-
-/* XXX: make it dynamic */
-StructEntry struct_entries[MAX_STRUCTS];
+static unsigned int max_struct_entries;
+StructEntry *struct_entries;
 
 static const argtype *thunk_type_next_ptr(const argtype *type_ptr);
 
@@ -70,6 +68,7 @@ void thunk_register_struct(int id, const char *name, const argtype *types)
     StructEntry *se;
     int nb_fields, offset, max_align, align, size, i, j;
 
+    assert(id < max_struct_entries);
     se = struct_entries + id;
 
     /* first we count the number of fields */
@@ -117,6 +116,8 @@ void thunk_register_struct_direct(int id, const char *name,
                                   const StructEntry *se1)
 {
     StructEntry *se;
+
+    assert(id < max_struct_entries);
     se = struct_entries + id;
     *se = *se1;
     se->name = name;
@@ -244,6 +245,7 @@ const argtype *thunk_convert(void *dst, const void *src,
             const argtype *field_types;
             const int *dst_offsets, *src_offsets;
 
+            assert(*type_ptr < max_struct_entries);
             se = struct_entries + *type_ptr++;
             if (se->convert[0] != NULL) {
                 /* specific conversion is needed */
@@ -314,3 +316,9 @@ int thunk_type_align_array(const argtype *type_ptr, int is_host)
     return thunk_type_align(type_ptr, is_host);
 }
 #endif /* ndef NO_THUNK_TYPE_SIZE */
+
+void thunk_init(unsigned int max_structs)
+{
+    max_struct_entries = max_structs;
+    struct_entries = g_new0(StructEntry, max_structs);
+}