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Port #12581 to SDL2

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This fixes undefined behavior resulting from adding offsets to nullptr.
This commit is contained in:
Derek Schuff
2025-05-01 23:19:50 +00:00
committed by Sam Lantinga
parent 2442c85cb8
commit a220e7c422
1 changed files with 7 additions and 6 deletions
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src/render/opengles2/SDL_render_gles2.c
+7 -6
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@@ -975,8 +975,8 @@ static int SetDrawState(GLES2_RenderData *data, const SDL_RenderCommand *cmd, co
} }
if (texture) { if (texture) {
SDL_Vertex *verts = (SDL_Vertex *)(((Uint8 *)vertices) + cmd->data.draw.first); uintptr_t base = (uintptr_t)vertices + cmd->data.draw.first; // address of first vertex, or base offset when using VBOs.
data->glVertexAttribPointer(GLES2_ATTRIBUTE_TEXCOORD, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)&verts->tex_coord); data->glVertexAttribPointer(GLES2_ATTRIBUTE_TEXCOORD, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)(base + offsetof(SDL_Vertex, tex_coord)));
} }
if (GLES2_SelectProgram(data, imgsrc, texture ? texture->w : 0, texture ? texture->h : 0) < 0) { if (GLES2_SelectProgram(data, imgsrc, texture ? texture->w : 0, texture ? texture->h : 0) < 0) {
@@ -1009,9 +1009,9 @@ static int SetDrawState(GLES2_RenderData *data, const SDL_RenderCommand *cmd, co
/* all drawing commands use this */ /* all drawing commands use this */
{ {
SDL_VertexSolid *verts = (SDL_VertexSolid *)(((Uint8 *)vertices) + cmd->data.draw.first); uintptr_t base = (uintptr_t)vertices + cmd->data.draw.first; // address of first vertex, or base offset when using VBOs.
data->glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)&verts->position); data->glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)(base + offsetof(SDL_VertexSolid, position)));
data->glVertexAttribPointer(GLES2_ATTRIBUTE_COLOR, 4, GL_UNSIGNED_BYTE, GL_TRUE /* Normalized */, stride, (const GLvoid *)&verts->color); data->glVertexAttribPointer(GLES2_ATTRIBUTE_COLOR, 4, GL_UNSIGNED_BYTE, GL_TRUE /* Normalized */, stride, (const GLvoid *)(base + offsetof(SDL_VertexSolid, color)));
} }
return 0; return 0;
@@ -1200,7 +1200,8 @@ static int GLES2_RunCommandQueue(SDL_Renderer *renderer, SDL_RenderCommand *cmd,
if (data->current_vertex_buffer >= SDL_arraysize(data->vertex_buffers)) { if (data->current_vertex_buffer >= SDL_arraysize(data->vertex_buffers)) {
data->current_vertex_buffer = 0; data->current_vertex_buffer = 0;
} }
vertices = NULL; /* attrib pointers will be offsets into the VBO. */ // attrib pointers will be offsets into the VBO.
vertices = (void *)(uintptr_t)0; // must be the exact value 0, not NULL (the representation of NULL is not guaranteed to be 0).
#endif #endif
while (cmd) { while (cmd) {