Re: KASAN: slab-out-of-bounds Read in handle_vmptrld

Robin Murphy
2019-09-13T15:32:57Z

On 13/09/2019 16:01, Paolo Bonzini wrote:
> On 13/09/19 15:02, Greg Kroah-Hartman wrote:
>> Look at linux-next, we "should" have fixed up hcd_buffer_alloc() now to
>> not need this type of thing. If we got it wrong, please let us know and
>> then yes, a fix like this would be most appreciated :)
>
> I still see
>
> /* some USB hosts just use PIO */
> if (!hcd_uses_dma(hcd)) {
> *dma = ~(dma_addr_t) 0;
> return kmalloc(size, mem_flags);
> }
>
> in linux-next's hcd_buffer_alloc and also in usb.git's usb-next branch.
> I also see the same
>
> if (remap_pfn_range(vma, vma->vm_start,
> virt_to_phys(usbm->mem) >> PAGE_SHIFT,
> size, vma->vm_page_prot) < 0) {
> ...
> }
>
> in usbdev_mmap. Of course it's possible that I'm looking at the wrong
> branch, or just being dense.

Oh, that bit of usbdev_mmap() is already known to be pretty much totally
bogus for various reasons - there have been a few threads about it, of
which I think [1] is both the most recent and the most informative.
There was another patch[2], but that might have stalled (and might need
reworking with additional hcd_uses_dma() checks anyway).

Robin.

[1]
https://lore.kernel.org/linux-arm-kernel/20190808084636.GB15080@priv-mua.localdomain/
[2]