From: Greg Kroah-Hartman gregkh@linuxfoundation.org
commit a0e710a7def471b8eb779ff551fc27701da49599 upstream.
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.
Fixes: 2bef9aed6f0e ("usb: usbfs: correct kernel->user page attribute mismatch") 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 Cc: stable stable@vger.kernel.org Reported-by: syzbot+353be47c9ce21b68b7ed@syzkaller.appspotmail.com Reviewed-by: Jeremy Linton jeremy.linton@arm.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20200514112711.1858252-1-gregkh@linuxfoundation.or... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/core/devio.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
--- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -251,9 +251,19 @@ static int usbdev_mmap(struct file *file 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;