ZYM: fix misaligned memory access

Signed-off-by: bones_was_here <bones_was_here@xonotic.au>

diff --git a/model_alias.c b/model_alias.c
index 8a7ae2b1be0709dd35f69a2c5073b7830e1e9d06..a18de3095dcc498534dbdb54ec979da5ef7a5698 100644 (file)
--- a/model_alias.c
+++ b/model_alias.c
@@ -1941,29 +1941,41 @@ void Mod_ZYMOTICMODEL_Load(model_t *mod, void *buffer, void *bufferend)
        loadmodel->submodelsurfaces_end = loadmodel->num_surfaces;
        loadmodel->num_textures = loadmodel->num_surfaces * loadmodel->numskins;
        loadmodel->num_texturesperskin = loadmodel->num_surfaces;
-       data = (unsigned char *)Mem_Alloc(loadmodel->mempool, loadmodel->num_surfaces * sizeof(msurface_t) + loadmodel->num_surfaces * sizeof(int) + loadmodel->num_surfaces * loadmodel->numskins * sizeof(texture_t) + meshtriangles * sizeof(int[3]) + (meshvertices <= 65536 ? meshtriangles * sizeof(unsigned short[3]) : 0) + meshvertices * (sizeof(float[14]) + sizeof(unsigned short) + sizeof(unsigned char[2][4])) + loadmodel->num_poses * loadmodel->num_bones * sizeof(short[7]) + loadmodel->num_bones * sizeof(float[12]));
-       loadmodel->data_surfaces = (msurface_t *)data;data += loadmodel->num_surfaces * sizeof(msurface_t);
-       loadmodel->modelsurfaces_sorted = (int *)data;data += loadmodel->num_surfaces * sizeof(int);
-       loadmodel->data_textures = (texture_t *)data;data += loadmodel->num_surfaces * loadmodel->numskins * sizeof(texture_t);
        loadmodel->surfmesh.num_vertices = meshvertices;
        loadmodel->surfmesh.num_triangles = meshtriangles;
-       loadmodel->surfmesh.data_element3i = (int *)data;data += meshtriangles * sizeof(int[3]);
-       loadmodel->surfmesh.data_vertex3f = (float *)data;data += meshvertices * sizeof(float[3]);
-       loadmodel->surfmesh.data_svector3f = (float *)data;data += meshvertices * sizeof(float[3]);
-       loadmodel->surfmesh.data_tvector3f = (float *)data;data += meshvertices * sizeof(float[3]);
-       loadmodel->surfmesh.data_normal3f = (float *)data;data += meshvertices * sizeof(float[3]);
-       loadmodel->surfmesh.data_texcoordtexture2f = (float *)data;data += meshvertices * sizeof(float[2]);
-       loadmodel->surfmesh.data_skeletalindex4ub = (unsigned char *)data;data += meshvertices * sizeof(unsigned char[4]);
-       loadmodel->surfmesh.data_skeletalweight4ub = (unsigned char *)data;data += meshvertices * sizeof(unsigned char[4]);
-       loadmodel->data_baseboneposeinverse = (float *)data;data += loadmodel->num_bones * sizeof(float[12]);
        loadmodel->surfmesh.num_blends = 0;
-       loadmodel->surfmesh.blends = (unsigned short *)data;data += meshvertices * sizeof(unsigned short);
+       loadmodel->surfmesh.data_blendweights = NULL;
+
+       // do most allocations as one merged chunk
+       // This is only robust for C standard types!
+       data = (unsigned char *)Mem_Alloc(loadmodel->mempool,
+               loadmodel->num_surfaces * sizeof(int)
+               + meshtriangles * sizeof(int[3])
+               + (meshvertices <= 65536 ? loadmodel->surfmesh.num_triangles * sizeof(unsigned short[3]) : 0)
+               + meshvertices * (sizeof(float[14]) + sizeof(unsigned short) + sizeof(unsigned char[2][4]))
+               + loadmodel->num_poses * loadmodel->num_bones * sizeof(short[7])
+               + loadmodel->num_bones * sizeof(float[12]));
+       // Pointers must be taken in descending order of alignment requirement!
+       loadmodel->surfmesh.data_vertex3f          = (float *)data; data += meshvertices * sizeof(float[3]);
+       loadmodel->surfmesh.data_svector3f         = (float *)data; data += meshvertices * sizeof(float[3]);
+       loadmodel->surfmesh.data_tvector3f         = (float *)data; data += meshvertices * sizeof(float[3]);
+       loadmodel->surfmesh.data_normal3f          = (float *)data; data += meshvertices * sizeof(float[3]);
+       loadmodel->surfmesh.data_texcoordtexture2f = (float *)data; data += meshvertices * sizeof(float[2]);
+       loadmodel->data_baseboneposeinverse        = (float *)data; data += loadmodel->num_bones * sizeof(float[12]);
+       loadmodel->modelsurfaces_sorted              = (int *)data; data += loadmodel->num_surfaces * sizeof(int);
+       loadmodel->surfmesh.data_element3i           = (int *)data; data += meshtriangles * sizeof(int[3]);
+       loadmodel->surfmesh.blends        = (unsigned short *)data; data += meshvertices * sizeof(unsigned short);
        if (loadmodel->surfmesh.num_vertices <= 65536)
        {
                loadmodel->surfmesh.data_element3s = (unsigned short *)data;data += loadmodel->surfmesh.num_triangles * sizeof(unsigned short[3]);
        }
-       loadmodel->data_poses7s = (short *)data;data += loadmodel->num_poses * loadmodel->num_bones * sizeof(short[7]);
-       loadmodel->surfmesh.data_blendweights = NULL;
+       loadmodel->data_poses7s                            = (short *)data; data += loadmodel->num_poses * loadmodel->num_bones * sizeof(short[7]);
+       loadmodel->surfmesh.data_skeletalindex4ub  = (unsigned char *)data; data += meshvertices * sizeof(unsigned char[4]);
+       loadmodel->surfmesh.data_skeletalweight4ub = (unsigned char *)data; data += meshvertices * sizeof(unsigned char[4]);
+       // Struct alignment requirements could change so we can't assume them here
+       // otherwise a safe-looking commit could introduce undefined behaviour!
+       loadmodel->data_surfaces = Mem_AllocType(loadmodel->mempool, msurface_t, loadmodel->num_surfaces * sizeof(msurface_t));
+       loadmodel->data_textures = Mem_AllocType(loadmodel->mempool, texture_t, loadmodel->num_surfaces * loadmodel->numskins * sizeof(texture_t));
 
        //zymlump_t lump_poses; // float pose[numposes][numbones][3][4]; // animation data
        poses = (float *) (pheader->lump_poses.start + pbase);