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https://aur.archlinux.org/linux-vfio.git
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70 lines
2.7 KiB
Diff
70 lines
2.7 KiB
Diff
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From a9fdf6354267d92b57bfb96fbcccbe5d5c163d8e Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Mon, 16 Oct 2017 16:21:19 +0200
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Subject: USB: devio: Revert "USB: devio: Don't corrupt user memory"
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commit 845d584f41eac3475c21e4a7d5e88d0f6e410cf7 upstream.
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Taking the uurb->buffer_length userspace passes in as a maximum for the
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actual urbs transfer_buffer_length causes 2 serious issues:
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1) It breaks isochronous support for all userspace apps using libusb,
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as existing libusb versions pass in 0 for uurb->buffer_length,
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relying on the kernel using the lenghts of the usbdevfs_iso_packet_desc
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descriptors passed in added together as buffer length.
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This for example causes redirection of USB audio and Webcam's into
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virtual machines using qemu-kvm to no longer work. This is a userspace
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ABI break and as such must be reverted.
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Note that the original commit does not protect other users / the
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kernels memory, it only stops the userspace process making the call
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from shooting itself in the foot.
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2) It may cause the kernel to program host controllers to DMA over random
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memory. Just as the devio code used to only look at the iso_packet_desc
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lenghts, the host drivers do the same, relying on the submitter of the
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urbs to make sure the entire buffer is large enough and not checking
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transfer_buffer_length.
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But the "USB: devio: Don't corrupt user memory" commit now takes the
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userspace provided uurb->buffer_length for the buffer-size while copying
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over the user-provided iso_packet_desc lengths 1:1, allowing the user
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to specify a small buffer size while programming the host controller to
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dma a lot more data.
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(Atleast the ohci, uhci, xhci and fhci drivers do not check
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transfer_buffer_length for isoc transfers.)
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This reverts commit fa1ed74eb1c2 ("USB: devio: Don't corrupt user memory")
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fixing both these issues.
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Cc: Dan Carpenter <dan.carpenter@oracle.com>
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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Acked-by: Alan Stern <stern@rowland.harvard.edu>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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drivers/usb/core/devio.c | 6 +-----
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1 file changed, 1 insertion(+), 5 deletions(-)
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diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
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index 1d4dfde..066b58c 100644
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--- a/drivers/usb/core/devio.c
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+++ b/drivers/usb/core/devio.c
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@@ -1576,11 +1576,7 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
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totlen += isopkt[u].length;
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}
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u *= sizeof(struct usb_iso_packet_descriptor);
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- if (totlen <= uurb->buffer_length)
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- uurb->buffer_length = totlen;
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- else
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- WARN_ONCE(1, "uurb->buffer_length is too short %d vs %d",
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- totlen, uurb->buffer_length);
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+ uurb->buffer_length = totlen;
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break;
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default:
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--
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cgit v1.1
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