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[PULL 12/24] hcd-ohci: Drop ohci_service_iso_td() if ed->head & OHCI_DPT
From: |
Gerd Hoffmann |
Subject: |
[PULL 12/24] hcd-ohci: Drop ohci_service_iso_td() if ed->head & OHCI_DPTR_MASK is zero |
Date: |
Tue, 27 Sep 2022 10:19:00 +0200 |
From: Qiang Liu <cyruscyliu@gmail.com>
An abort happens in ohci_frame_boundary() when ohci->done is 0 [1].
``` c
static void ohci_frame_boundary(void *opaque)
{
// ...
if (ohci->done_count == 0 && !(ohci->intr_status & OHCI_INTR_WD)) {
if (!ohci->done)
abort(); <----------------------------------------- [1]
```
This was reported in https://bugs.launchpad.net/qemu/+bug/1911216/,
https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg03613.html, and
https://gitlab.com/qemu-project/qemu/-/issues/545. I can still reproduce it with
the latest QEMU.
This happends due to crafted ED with putting ISO_TD at physical address 0.
Suppose ed->head & OHCI_DPTR_MASK is 0 [2], and we memset 0 to the phyiscal
memory from 0 to sizeof(ohci_iso_td). Then, starting_frame [3] and frame_count
[4] are both 0. As we can control the value of ohci->frame_number (0 to 0x1f,
suppose 1), we then control the value of relative_frame_number to be 1 [6]. The
control flow goes to [7] where ohci->done is 0. Have returned from
ohci_service_iso_td(), ohci_frame_boundary() will abort() [1].
``` c
static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed)
{
// ...
addr = ed->head & OHCI_DPTR_MASK; // <--------------------- [2]
if (ohci_read_iso_td(ohci, addr, &iso_td)) { // <-------- [3]
// ...
starting_frame = OHCI_BM(iso_td.flags, TD_SF); // <-------- [4]
frame_count = OHCI_BM(iso_td.flags, TD_FC); // <-------- [5]
relative_frame_number = USUB(ohci->frame_number, starting_frame);
// <-------- [6]
if (relative_frame_number < 0) {
return 1;
} else if (relative_frame_number > frame_count) {
// ...
ohci->done = addr; // <-------- [7]
// ...
}
```
As only (afaik) a guest root user can manipulate ED, TD and the physical memory,
this assertion failure is not a security bug.
The idea to fix this issue is to drop ohci_service_iso_td() if ed->head &
OHCI_DPTR_MASK is 0, which is similar to the drop operation for
ohci_service_ed_list() when head is 0. Probably, a similar issue is in
ohci_service_td(). I drop ohci_service_td() if ed->head & OHCI_DPTR_MASK is 0.
Fixes: 7bfe577702 ("OHCI USB isochronous transfers support (Arnon Gilboa)")
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Reported-by: Alexander Bulekov <alxndr@bu.edu>
Reported-by: Qiang Liu <cyruscyliu@gmail.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/545
Buglink: https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg03613.html
Buglink: https://bugs.launchpad.net/qemu/+bug/1911216
Signed-off-by: Qiang Liu <cyruscyliu@gmail.com>
Message-Id: <20220826051557.119570-1-cyruscyliu@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
hw/usb/hcd-ohci.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
index 895b29fb8657..72bdde92617c 100644
--- a/hw/usb/hcd-ohci.c
+++ b/hw/usb/hcd-ohci.c
@@ -571,6 +571,11 @@ static int ohci_service_iso_td(OHCIState *ohci, struct
ohci_ed *ed)
addr = ed->head & OHCI_DPTR_MASK;
+ if (addr == 0) {
+ ohci_die(ohci);
+ return 1;
+ }
+
if (ohci_read_iso_td(ohci, addr, &iso_td)) {
trace_usb_ohci_iso_td_read_failed(addr);
ohci_die(ohci);
@@ -858,6 +863,11 @@ static int ohci_service_td(OHCIState *ohci, struct ohci_ed
*ed)
int completion;
addr = ed->head & OHCI_DPTR_MASK;
+ if (addr == 0) {
+ ohci_die(ohci);
+ return 1;
+ }
+
/* See if this TD has already been submitted to the device. */
completion = (addr == ohci->async_td);
if (completion && !ohci->async_complete) {
--
2.37.3
- [PULL 10/24] ui/console: fix three double frees in png_save(), (continued)
- [PULL 10/24] ui/console: fix three double frees in png_save(), Gerd Hoffmann, 2022/09/27
- [PULL 09/24] ui/vdagent: fix serial reset of guest agent, Gerd Hoffmann, 2022/09/27
- [PULL 03/24] Revert "main-loop: Disable block backend global state assertion on Cocoa", Gerd Hoffmann, 2022/09/27
- [PULL 02/24] ui/cocoa: Run qemu_init in the main thread, Gerd Hoffmann, 2022/09/27
- [PULL 06/24] ui/clipboard: fix serial priority, Gerd Hoffmann, 2022/09/27
- [PULL 11/24] hw/usb/hcd-xhci: Check whether DMA accesses fail, Gerd Hoffmann, 2022/09/27
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- [PULL 16/24] usbnet: Add missing usb_wakeup() call in usbnet_receive(), Gerd Hoffmann, 2022/09/27
- [PULL 14/24] usb/msd: add usb_msd_fatal_error() and fix guest-triggerable assert, Gerd Hoffmann, 2022/09/27
- [PULL 15/24] hcd-xhci: drop operation with secondary stream arrays enabled, Gerd Hoffmann, 2022/09/27
- [PULL 12/24] hcd-ohci: Drop ohci_service_iso_td() if ed->head & OHCI_DPTR_MASK is zero,
Gerd Hoffmann <=
- [PULL 13/24] usb/msd: move usb_msd_packet_complete(), Gerd Hoffmann, 2022/09/27
- [PULL 19/24] usbnet: Report link-up via interrupt endpoint in CDC-ECM mode, Gerd Hoffmann, 2022/09/27
- [PULL 18/24] usbnet: Detect short packets as sent by the xHCI controller, Gerd Hoffmann, 2022/09/27
- [PULL 17/24] usbnet: Accept mandatory USB_CDC_SET_ETHERNET_PACKET_FILTER request, Gerd Hoffmann, 2022/09/27
- [PULL 24/24] virtio-gpu: update scanout if there is any area covered by the rect, Gerd Hoffmann, 2022/09/27
- [PULL 21/24] Revert "audio: Log context for audio bug", Gerd Hoffmann, 2022/09/27
- [PULL 20/24] audio: Add sndio backend, Gerd Hoffmann, 2022/09/27
- [PULL 22/24] audio: remove abort() in audio_bug(), Gerd Hoffmann, 2022/09/27
- [PULL 23/24] hw/display/ati_2d: Fix buffer overflow in ati_2d_blt (CVE-2021-3638), Gerd Hoffmann, 2022/09/27
- Re: [PULL 00/24] Kraxel 20220927 patches, Stefan Hajnoczi, 2022/09/27