CVE-2020-25625: Re: [PATCH v2 2/2] hw: usb: hcd-ohci: check for processed TD before reti

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From:

Li Qiang

Subject:

Re: [PATCH v2 2/2] hw: usb: hcd-ohci: check for processed TD before retire

Date:

Wed, 16 Sep 2020 22:51:56 +0800

P J P [email protected] 于2020年9月16日周三 上午2:25写道：

From: Prasad J Pandit [email protected]

Reviewed-by: Li Qiang [email protected]

While servicing OHCI transfer descriptors(TD), ohci_service_iso_td retires a TD if it has passed its time frame. It does not check if the TD was already processed once and holds an error code in TD_CC. It may happen if the TD list has a loop. Add check to avoid an infinite loop condition.

Signed-off-by: Prasad J Pandit [email protected] — hw/usb/hcd-ohci.c | 4 ++++ 1 file changed, 4 insertions(+)

Update v2: one patch for loop issue -> https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05145.html

diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c index 9dc59101f9…8b912e95d3 100644 — a/hw/usb/hcd-ohci.c +++ b/hw/usb/hcd-ohci.c @@ -691,6 +691,10 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed, the next ISO TD of the same ED */

trace_usb_ohci_iso_td_relative_frame_number_big(relative_frame_number, frame_count); + if (OHCI_CC_DATAOVERRUN == OHCI_BM(iso_td.flags, TD_CC)) { + /* avoid infinite loop */ + return 1; + } OHCI_SET_BM(iso_td.flags, TD_CC, OHCI_CC_DATAOVERRUN); ed->head &= ~OHCI_DPTR_MASK; ed->head |= (iso_td.next & OHCI_DPTR_MASK); – 2.26.2

• [PATCH v2 0/2] hw: usb: hcd-ohci: fix oob access and loop issues, P J P, 2020/09/15

  • [PATCH v2 2/2] hw: usb: hcd-ohci: check for processed TD before retire, P J P, 2020/09/15
    • Re: [PATCH v2 2/2] hw: usb: hcd-ohci: check for processed TD before retire, Li Qiang <=
  • [PATCH v2 1/2] hw: usb: hcd-ohci: check len and frame_number variables, P J P, 2020/09/15
  • Re: [PATCH v2 0/2] hw: usb: hcd-ohci: fix oob access and loop issues, Gerd Hoffmann, 2020/09/21

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