From 2bef9aed6f0e22391c8d4570749b1acc9bc3981e Mon Sep 17 00:00:00 2001 From: Jeremy Linton Date: Mon, 4 May 2020 15:13:48 -0500 Subject: usb: usbfs: correct kernel->user page attribute mismatch On some architectures (e.g. arm64) requests for IO coherent memory may use non-cachable attributes if the relevant device isn't cache coherent. If these pages are then remapped into userspace as cacheable, they may not be coherent with the non-cacheable mappings. In particular this happens with libusb, when it attempts to create zero-copy buffers for use by rtl-sdr (https://github.com/osmocom/rtl-sdr/). On low end arm devices with non-coherent USB ports, the application will be unexpectedly killed, while continuing to work fine on arm machines with coherent USB controllers. This bug has been discovered/reported a few times over the last few years. In the case of rtl-sdr a compile time option to enable/disable zero copy was implemented to work around it. Rather than relaying on application specific workarounds, dma_mmap_coherent() can be used instead of remap_pfn_range(). The page cache/etc attributes will then be correctly set in userspace to match the kernel mapping. Signed-off-by: Jeremy Linton Cc: stable Link: https://lore.kernel.org/r/20200504201348.1183246-1-jeremy.linton@arm.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/devio.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'drivers/usb/core/devio.c') diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 6833c918abce..b9db9812d6c5 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -217,6 +217,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) { struct usb_memory *usbm = NULL; struct usb_dev_state *ps = file->private_data; + struct usb_hcd *hcd = bus_to_hcd(ps->dev->bus); size_t size = vma->vm_end - vma->vm_start; void *mem; unsigned long flags; @@ -250,9 +251,7 @@ static int usbdev_mmap(struct file *file, struct vm_area_struct *vma) usbm->vma_use_count = 1; INIT_LIST_HEAD(&usbm->memlist); - if (remap_pfn_range(vma, vma->vm_start, - virt_to_phys(usbm->mem) >> PAGE_SHIFT, - size, vma->vm_page_prot) < 0) { + if (dma_mmap_coherent(hcd->self.sysdev, vma, mem, dma_handle, size)) { dec_usb_memory_use_count(usbm, &usbm->vma_use_count); return -EAGAIN; } -- cgit v1.2.3 From a0e710a7def471b8eb779ff551fc27701da49599 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 14 May 2020 13:27:11 +0200 Subject: USB: usbfs: fix mmap dma mismatch 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(-) (limited to 'drivers/usb/core/devio.c') 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; -- cgit v1.2.3