From 633ffd285cde3e7a8533220fce949003d382a54e 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 In commit 765e3c26f513 ("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: 765e3c26f513 ("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 b9db9812d6c5e..d93d94d7ff506 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; -- 2.39.5