mesa: fix error handling for dlist image unpacking

When compiling glDrawPixels, glTexImage(), etc. and we're copying
the user's image we need to be careful about GL error checking.
Previously, we were incorrectly generating GL_OUT_OF_MEMORY in
unpack_image() if width <= 0 or height <= 0 or for invalid format/type
values.  We now check those arguments in unpack_image() and return NULL
if there's a bad value.  The command will get compiled with the
arguments as-is and image=NULL.  Later, when the command is executed the
correct errors will be generated.

This issue was reported by Yuanhan Liu <yuanhan.liu@linux.intel.com>

Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>

src/mesa/main/dlist.c

@@ -871,7 +871,11 @@ translate_id(GLsizei n, GLenum type, const GLvoid * list)
 
 /**
  * Wrapper for _mesa_unpack_image() that handles pixel buffer objects.
- * If we run out of memory, GL_OUT_OF_MEMORY will be recorded.
+ * If width < 0 or height < 0 or format or type are invalid we'll just
+ * return NULL.  We will not generate an error since OpenGL command
+ * arguments aren't error-checked until the command is actually executed
+ * (not when they're compiled).
+ * But if we run out of memory, GL_OUT_OF_MEMORY will be recorded.
  */
 static GLvoid *
 unpack_image(struct gl_context *ctx, GLuint dimensions,
@@ -879,6 +883,15 @@ unpack_image(struct gl_context *ctx, GLuint dimensions,
              GLenum format, GLenum type, const GLvoid * pixels,
              const struct gl_pixelstore_attrib *unpack)
 {
+   if (width <= 0 || height <= 0) {
+      return NULL;
+   }
+
+   if (_mesa_bytes_per_pixel(format, type) <= 0) {
+      /* bad format and/or type */
+      return NULL;
+   }
+
    if (!_mesa_is_bufferobj(unpack->BufferObj)) {
       /* no PBO */
       GLvoid *image = _mesa_unpack_image(dimensions, width, height, depth,