From c737b7533596c45d5ee884099cfa58200bdf5a1b Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 14 May 2020 13:27:11 +0200 Subject: [PATCH] USB: usbfs: fix mmap dma mismatch 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 Cc: Hillf Danton Cc: Thomas Gleixner Cc: Jeremy Linton Cc: stable Reported-by: syzbot+353be47c9ce21b68b7ed@syzkaller.appspotmail.com Reviewed-by: Jeremy Linton Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20200514112711.1858252-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman --- 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 162261f0ad28..e26a6f18f421 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;