OpenGL texture contains bad data - what's going on?

I am trying to load an image into OpenGL texture.

I created a window and GL 4.4 Core Forward-Compatible context:

Here's the code I'm using to load the image and create the texture:

load :: IO ()
load = do
    image <- JP.readImage "image.png"
    case image of
        (Left err) -> do print err
                         exitWith (ExitFailure 1)
        (Right imgData) -> do 
            a <- malloc
            glGenTextures 1 a
            texId <- peek a
            free a
            loadImgIntoTexture texId imgData

loadImgIntoTexture texId (JP.ImageRGBA8 (JP.Image width height dat)) = do
    glBindTexture GL_TEXTURE_2D texId
    unsafeWith dat $ glTexImage2D GL_TEXTURE_2D 0 GL_RGBA (fromIntegral width) (fromIntegral height) 0 GL_RGBA GL_UNSIGNED_BYTE . castPtr
    --p <- mallocBytes $ (fromIntegral width) * (fromIntegral height) * 4
    --glTexImage2D GL_TEXTURE_2D 0 GL_RGBA (fromIntegral width) (fromIntegral height) 0 GL_RGBA GL_UNSIGNED_BYTE (castPtr p)
    print "everything ok"

The commented out line is another attempt to put anything meaningful into that texture.

Here's what gDebugger reports for the texture information:

And here's what it shows for the texture contents:

When I print out the structure returned by JuicyPixels, it prints out distinct byte sequences that most certainly don't produce a flat image.

In this example I'm not rendering the texture, and I'm using raw binding generated by the gl package. I had exactly the same behaviour (with the same shade of teal) when using OpenGL package. It unsurprisingly rendered as a flat rectangle on the screen.

I have tried with different images, sized 128x128 and NPOT (100x100 as in the screenshots).

What could be causing that behaviour?

Full source.

This is most probably the bug in gDEBugger. After some manipulations and actually drawing the texture, I've verified that it indeed contains the right data.