Messages in this thread | | | Date | Mon, 15 Oct 2007 03:01:57 +0100 | From | Al Viro <> | Subject | [RFC] vivi, videobuf_to_vmalloc() and related breakage |
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AFAICS, videobuf-vmalloc use of mem->vma and mem->vmalloc is bogus.
You obtain the latter with vmalloc_user(); so far, so good. Then you have retval=remap_vmalloc_range(vma, mem->vmalloc,0); where vma is given to you by mmap(); again, fine - we get the memory pointed to be mem->vmalloc() mapped at vma->vm_start.
Now we get the trouble: things like
static void vivi_fillbuff(struct vivi_dev *dev,struct vivi_buffer *buf) { ... void *vbuf=videobuf_to_vmalloc (&buf->vb); ... copy_to_user(vbuf + ..., ..., ...)
get vbuf equal to ->vmalloc of buf->vp.priv and that is _not_ a userland address. Giving it to copy_to_user() is not going to do anything good. On some targets it'll fail, on some - write to unrelated user memory. What is going on there? If that's an attempt to copy into that buffer allocated by vmalloc_user(), why are we doing copy_to_user() at all?
But there's more; we have made a copy of vma (kmalloc+memcpy), stored it in mem->vma and later we cheerfully do remap_vmalloc_range(mem->vma,....). And kfree that mem->vma immediately afterwards. What the hell? It might not break now, but that seems to be playing very fast and loose with the warranties provided by VM. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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