112 lines
4.1 KiB
Diff
112 lines
4.1 KiB
Diff
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From 11d2262ba82c29dd3b6bdfe1e40f57efad550ffc Mon Sep 17 00:00:00 2001
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From: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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Date: Sat, 12 Oct 2024 09:47:17 +0000
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Subject: [PATCH] hcd-ohci: Drop ohci_service_iso_td() if ed->head &
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OHCI_DPTR_MASK is zero mainline inclusion commit
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d8c2e6f2f6d29ccb766197181eb1c65c1d46b3a4 category: bugfix
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---------------------------------------------------------------
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An abort happens in ohci_frame_boundary() when ohci->done is 0 [1].
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``` c
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static void ohci_frame_boundary(void *opaque)
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{
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// ...
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if (ohci->done_count == 0 && !(ohci->intr_status & OHCI_INTR_WD)) {
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if (!ohci->done)
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abort(); <----------------------------------------- [1]
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```
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This was reported in https://bugs.launchpad.net/qemu/+bug/1911216/,
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https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg03613.html, and
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https://gitlab.com/qemu-project/qemu/-/issues/545. I can still reproduce it with
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the latest QEMU.
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This happends due to crafted ED with putting ISO_TD at physical address 0.
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Suppose ed->head & OHCI_DPTR_MASK is 0 [2], and we memset 0 to the phyiscal
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memory from 0 to sizeof(ohci_iso_td). Then, starting_frame [3] and frame_count
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[4] are both 0. As we can control the value of ohci->frame_number (0 to 0x1f,
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suppose 1), we then control the value of relative_frame_number to be 1 [6]. The
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control flow goes to [7] where ohci->done is 0. Have returned from
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ohci_service_iso_td(), ohci_frame_boundary() will abort() [1].
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``` c
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static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed)
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{
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// ...
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addr = ed->head & OHCI_DPTR_MASK; // <--------------------- [2]
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if (ohci_read_iso_td(ohci, addr, &iso_td)) { // <-------- [3]
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// ...
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starting_frame = OHCI_BM(iso_td.flags, TD_SF); // <-------- [4]
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frame_count = OHCI_BM(iso_td.flags, TD_FC); // <-------- [5]
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relative_frame_number = USUB(ohci->frame_number, starting_frame);
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// <-------- [6]
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if (relative_frame_number < 0) {
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return 1;
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} else if (relative_frame_number > frame_count) {
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// ...
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ohci->done = addr; // <-------- [7]
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// ...
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}
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```
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As only (afaik) a guest root user can manipulate ED, TD and the physical memory,
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this assertion failure is not a security bug.
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The idea to fix this issue is to drop ohci_service_iso_td() if ed->head &
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OHCI_DPTR_MASK is 0, which is similar to the drop operation for
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ohci_service_ed_list() when head is 0. Probably, a similar issue is in
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ohci_service_td(). I drop ohci_service_td() if ed->head & OHCI_DPTR_MASK is 0.
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Fixes: 7bfe577702 ("OHCI USB isochronous transfers support (Arnon Gilboa)")
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Reported-by: Gaoning Pan <pgn@zju.edu.cn>
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Reported-by: Alexander Bulekov <alxndr@bu.edu>
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Reported-by: Qiang Liu <cyruscyliu@gmail.com>
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/545
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Buglink: https://lists.gnu.org/archive/html/qemu-devel/2021-06/msg03613.html
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Buglink: https://bugs.launchpad.net/qemu/+bug/1911216
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Signed-off-by: Qiang Liu <cyruscyliu@gmail.com>
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Message-Id: <20220826051557.119570-1-cyruscyliu@gmail.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Signed-off-by: tangbinzy <tangbin_yewu@cmss.chinamobile.com>
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---
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hw/usb/hcd-ohci.c | 10 ++++++++++
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1 file changed, 10 insertions(+)
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diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
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index a93d6b2e98..d6f1ae700e 100644
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--- a/hw/usb/hcd-ohci.c
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+++ b/hw/usb/hcd-ohci.c
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@@ -668,6 +668,11 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed,
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addr = ed->head & OHCI_DPTR_MASK;
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+ if (addr == 0) {
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+ ohci_die(ohci);
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+ return 1;
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+ }
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+
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if (ohci_read_iso_td(ohci, addr, &iso_td)) {
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trace_usb_ohci_iso_td_read_failed(addr);
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ohci_die(ohci);
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@@ -953,6 +958,11 @@ static int ohci_service_td(OHCIState *ohci, struct ohci_ed *ed)
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int completion;
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addr = ed->head & OHCI_DPTR_MASK;
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+ if (addr == 0) {
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+ ohci_die(ohci);
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+ return 1;
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+ }
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+
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/* See if this TD has already been submitted to the device. */
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completion = (addr == ohci->async_td);
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if (completion && !ohci->async_complete) {
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--
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2.41.0.windows.1
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