Messages in this thread | | | Subject | Re: [PATCH] USB: usbfs: fix mmap dma mismatch | From | Jeremy Linton <> | Date | Thu, 14 May 2020 06:37:25 -0500 |
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Hi,
So looking at hcd_buffer_alloc() again, there are 4 cases, localmem_pool, hcd_uses_dma, dma_pool_alloc and dma_alloc_coherent directly. The dma_pool_alloc appears to just be using dma_alloc_coherent, so its really three cases.
Those three cases appear to be handled below:
So:
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
I'm testing it now...
Thanks,
On 5/14/20 6:27 AM, Greg Kroah-Hartman wrote: > In commit 2bef9aed6f0e ("usb: usbfs: correct kernel->user page attribute > mismatch") we switched from always calling remap_pfn_range() to call > dma_mmap_coherent() to handle issues with systems with non-coherent USB host > controller drivers. Unfortunatly, as syzbot quickly told us, not all the world > is host controllers with DMA support, so we need to check what host controller > we are attempting to talk to before doing this type of allocation. > > Thanks to Christoph for the quick idea of how to fix this. > > Cc: Christoph Hellwig <hch@lst.de> > Cc: Hillf Danton <hdanton@sina.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Jeremy Linton <jeremy.linton@arm.com> > Reported-by: syzbot+353be47c9ce21b68b7ed@syzkaller.appspotmail.com > Fixes: 2bef9aed6f0e ("usb: usbfs: correct kernel->user page attribute mismatch") > Cc: stable <stable@vger.kernel.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > --- > drivers/usb/core/devio.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c > index b9db9812d6c5..d93d94d7ff50 100644 > --- a/drivers/usb/core/devio.c > +++ b/drivers/usb/core/devio.c > @@ -251,9 +251,19 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) > usbm->vma_use_count = 1; > INIT_LIST_HEAD(&usbm->memlist); > > - if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle, size)) { > - dec_usb_memory_use_count(usbm, &usbm->vma_use_count); > - return -EAGAIN; > + if (hcd->localmem_pool || !hcd_uses_dma(hcd)) { > + if (remap_pfn_range(vma, vma->vm_start, > + virt_to_phys(usbm->mem) >> PAGE_SHIFT, > + size, vma->vm_page_prot) < 0) { > + dec_usb_memory_use_count(usbm, &usbm->vma_use_count); > + return -EAGAIN; > + } > + } else { > + if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle, > + size)) { > + dec_usb_memory_use_count(usbm, &usbm->vma_use_count); > + return -EAGAIN; > + } > } > > vma->vm_flags |= VM_IO; >
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