From 0dbe4768b95eef1d0fa55a5cfd6ec7a6ffa58634 Mon Sep 17 00:00:00 2001
From: Nick Rosbrook <rosbrookn@gmail.com>
Date: Mon, 1 Feb 2021 16:30:21 -0500
Subject: [PATCH 1/2] usb-host: use correct altsetting in usb_host_ep_update
In order to keep track of the alternate setting that should be used for
a given interface, the USBDevice struct keeps an array of alternate
setting values, which is indexed by the interface number. In
usb_host_set_interface, when this array is updated, usb_host_ep_update
is called as a result. However, when usb_host_ep_update accesses the
active libusb_config_descriptor, it indexes udev->altsetting with the
loop variable, rather than the interface number.
With the simple trace backend enable, this behavior can be seen:
[...]
usb_xhci_xfer_start 0.440 pid=1215 xfer=0x5596a4b85930 slotid=0x1 epid=0x1 streamid=0x0
usb_packet_state_change 1.703 pid=1215 bus=0x1 port=b'1' ep=0x0 p=0x5596a4b85938 o=b'undef' n=b'setup'
usb_host_req_control 2.269 pid=1215 bus=0x1 addr=0x5 p=0x5596a4b85938 req=0x10b value=0x1 index=0xd
usb_host_set_interface 0.449 pid=1215 bus=0x1 addr=0x5 interface=0xd alt=0x1
usb_host_parse_config 2542.648 pid=1215 bus=0x1 addr=0x5 value=0x2 active=0x1
usb_host_parse_interface 1.804 pid=1215 bus=0x1 addr=0x5 num=0xc alt=0x0 active=0x1
usb_host_parse_endpoint 2.012 pid=1215 bus=0x1 addr=0x5 ep=0x2 dir=b'in' type=b'int' active=0x1
usb_host_parse_interface 1.598 pid=1215 bus=0x1 addr=0x5 num=0xd alt=0x0 active=0x1
usb_host_req_emulated 3.593 pid=1215 bus=0x1 addr=0x5 p=0x5596a4b85938 status=0x0
usb_packet_state_change 2.550 pid=1215 bus=0x1 port=b'1' ep=0x0 p=0x5596a4b85938 o=b'setup' n=b'complete'
usb_xhci_xfer_success 4.298 pid=1215 xfer=0x5596a4b85930 bytes=0x0
[...]
In particular, it is seen that although usb_host_set_interface sets the
alternate setting of interface 0xd to 0x1, usb_host_ep_update uses 0x0
as the alternate setting due to using the incorrect index to
udev->altsetting.
Fix this problem by getting the interface number from the active
libusb_config_descriptor, and then using that as the index to
udev->altsetting.
Signed-off-by: Nick Rosbrook <rosbrookn@ainfosec.com>
Message-Id: <20210201213021.500277-1-rosbrookn@ainfosec.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
hw/usb/host-libusb.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/hw/usb/host-libusb.c b/hw/usb/host-libusb.c
index 7dde3d1206..354713a77d 100644
--- a/hw/usb/host-libusb.c
+++ b/hw/usb/host-libusb.c
@@ -836,7 +836,7 @@ static void usb_host_ep_update(USBHostDevice *s)
struct libusb_ss_endpoint_companion_descriptor *endp_ss_comp;
#endif
uint8_t devep, type;
- int pid, ep;
+ int pid, ep, alt;
int rc, i, e;
usb_ep_reset(udev);
@@ -848,8 +848,20 @@ static void usb_host_ep_update(USBHostDevice *s)
conf->bConfigurationValue, true);
for (i = 0; i < conf->bNumInterfaces; i++) {
- assert(udev->altsetting[i] < conf->interface[i].num_altsetting);
- intf = &conf->interface[i].altsetting[udev->altsetting[i]];
+ /*
+ * The udev->altsetting array indexes alternate settings
+ * by the interface number. Get the 0th alternate setting
+ * first so that we can grab the interface number, and
+ * then correct the alternate setting value if necessary.
+ */
+ intf = &conf->interface[i].altsetting[0];
+ alt = udev->altsetting[intf->bInterfaceNumber];
+
+ if (alt != 0) {
+ assert(alt < conf->interface[i].num_altsetting);
+ intf = &conf->interface[i].altsetting[alt];
+ }
+
trace_usb_host_parse_interface(s->bus_num, s->addr,
intf->bInterfaceNumber,
intf->bAlternateSetting, true);
From 6ba5a437ad48f10931592f649b5b7375968f362d Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Tue, 16 Feb 2021 15:49:39 +0100
Subject: [PATCH 2/2] usb/pcap: set flag_setup
Without that wireshark complains about invalid control setup data
for non-control transfers.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20210216144939.841873-1-kraxel@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
hw/usb/pcap.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/hw/usb/pcap.c b/hw/usb/pcap.c
index 4350989d3a..dbff00be25 100644
--- a/hw/usb/pcap.c
+++ b/hw/usb/pcap.c
@@ -127,6 +127,7 @@ static void do_usb_pcap_ctrl(FILE *fp, USBPacket *p, bool setup)
.xfer_type = usbmon_xfer_type[USB_ENDPOINT_XFER_CONTROL],
.epnum = in ? 0x80 : 0,
.devnum = dev->addr,
+ .flag_setup = setup ? 0 : '-',
.flag_data = '=',
.length = dev->setup_len,
};
@@ -169,6 +170,7 @@ static void do_usb_pcap_data(FILE *fp, USBPacket *p, bool setup)
.xfer_type = usbmon_xfer_type[p->ep->type],
.epnum = usbmon_epnum(p),
.devnum = p->ep->dev->addr,
+ .flag_setup = '-',
.flag_data = '=',
.length = p->iov.size,
};