OpenGL with SDL, what am I doing wrong?

OpenGL with SDL, what am I doing wrong?

I'm trying to display simple white cube in OpenGL with SDL. I've setup my
VBO and IBO like this:
GLfloat vertexData[] =
{
-0.5f, -0.5f, -0.5f, // bot, left, back
-0.5f, 0.5f, -0.5f, // top, left, back
-0.5f, -0.5f, 0.5f, // bot, left, front
-0.5f, 0.5f, 0.5f, // top, left, front
0.5f, -0.5f, -0.5f, // bot, right, back
0.5f, -0.5f, 0.5f, // bot, right, front
0.5f, 0.5f, -0.5f, // top, right, back
0.5f, 0.5f, 0.5f // top, right, front
};
GLint indexData[] =
{
//back
0, 1, 6,
0, 5, 6,
//left
0, 2, 3,
0, 1, 3,
//right
4, 5, 7,
4, 6, 7,
//bot
0, 4, 5,
0, 2, 5,
//top
1, 3, 7,
1, 6, 7,
//front
2, 3, 7,
2, 5, 7
};
However, it looks like this:
What am I doing wrong? Thanks for your answers.