| Message ID | 20191219161016.6695-1-johan@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 3e4f8e21c4f27bcf30a48486b9dcc269512b79ff |
| Headers | show |
| Series | USB: core: fix check for duplicate endpoints | expand |
On Thu, 19 Dec 2019, Johan Hovold wrote: > Amend the endpoint-descriptor sanity checks to detect all duplicate > endpoint addresses in a configuration. > > Commit 0a8fd1346254 ("USB: fix problems with duplicate endpoint > addresses") added a check for duplicate endpoint addresses within a > single alternate setting, but did not look for duplicate addresses in > other interfaces. > > The current check would also not detect all duplicate addresses when one > endpoint is as a (bi-directional) control endpoint. > > This specifically avoids overwriting the endpoint entries in struct > usb_device when enabling a duplicate endpoint, something which could > potentially lead to crashes or leaks, for example, when endpoints are > later disabled. > > Cc: stable <stable@vger.kernel.org> > Signed-off-by: Johan Hovold <johan@kernel.org> > --- > > Exploiting this to trigger a crash probably requires a lot more > malicious intent than the syzbot fuzzer currently possesses, but I think > we need to plug this nonetheless. > > Johan This is a good improvement. Acked-by: Alan Stern <stern@rowland.harvard.edu> Alan Stern > drivers/usb/core/config.c | 70 ++++++++++++++++++++++++++++++++------- > 1 file changed, 58 insertions(+), 12 deletions(-) > > diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c > index 5f40117e68e7..21291950cc97 100644 > --- a/drivers/usb/core/config.c > +++ b/drivers/usb/core/config.c > @@ -203,9 +203,58 @@ static const unsigned short super_speed_maxpacket_maxes[4] = { > [USB_ENDPOINT_XFER_INT] = 1024, > }; > > -static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum, > - int asnum, struct usb_host_interface *ifp, int num_ep, > - unsigned char *buffer, int size) > +static bool endpoint_is_duplicate(struct usb_endpoint_descriptor *e1, > + struct usb_endpoint_descriptor *e2) > +{ > + if (e1->bEndpointAddress == e2->bEndpointAddress) > + return true; > + > + if (usb_endpoint_xfer_control(e1) || usb_endpoint_xfer_control(e2)) { > + if (usb_endpoint_num(e1) == usb_endpoint_num(e2)) > + return true; > + } > + > + return false; > +} > + > +/* > + * Check for duplicate endpoint addresses in other interfaces and in the > + * altsetting currently being parsed. > + */ > +static bool config_endpoint_is_duplicate(struct usb_host_config *config, > + int inum, int asnum, struct usb_endpoint_descriptor *d) > +{ > + struct usb_endpoint_descriptor *epd; > + struct usb_interface_cache *intfc; > + struct usb_host_interface *alt; > + int i, j, k; > + > + for (i = 0; i < config->desc.bNumInterfaces; ++i) { > + intfc = config->intf_cache[i]; > + > + for (j = 0; j < intfc->num_altsetting; ++j) { > + alt = &intfc->altsetting[j]; > + > + if (alt->desc.bInterfaceNumber == inum && > + alt->desc.bAlternateSetting != asnum) > + continue; > + > + for (k = 0; k < alt->desc.bNumEndpoints; ++k) { > + epd = &alt->endpoint[k].desc; > + > + if (endpoint_is_duplicate(epd, d)) > + return true; > + } > + } > + } > + > + return false; > +} > + > +static int usb_parse_endpoint(struct device *ddev, int cfgno, > + struct usb_host_config *config, int inum, int asnum, > + struct usb_host_interface *ifp, int num_ep, > + unsigned char *buffer, int size) > { > unsigned char *buffer0 = buffer; > struct usb_endpoint_descriptor *d; > @@ -242,13 +291,10 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum, > goto skip_to_next_endpoint_or_interface_descriptor; > > /* Check for duplicate endpoint addresses */ > - for (i = 0; i < ifp->desc.bNumEndpoints; ++i) { > - if (ifp->endpoint[i].desc.bEndpointAddress == > - d->bEndpointAddress) { > - dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n", > - cfgno, inum, asnum, d->bEndpointAddress); > - goto skip_to_next_endpoint_or_interface_descriptor; > - } > + if (config_endpoint_is_duplicate(config, inum, asnum, d)) { > + dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n", > + cfgno, inum, asnum, d->bEndpointAddress); > + goto skip_to_next_endpoint_or_interface_descriptor; > } > > endpoint = &ifp->endpoint[ifp->desc.bNumEndpoints]; > @@ -522,8 +568,8 @@ static int usb_parse_interface(struct device *ddev, int cfgno, > if (((struct usb_descriptor_header *) buffer)->bDescriptorType > == USB_DT_INTERFACE) > break; > - retval = usb_parse_endpoint(ddev, cfgno, inum, asnum, alt, > - num_ep, buffer, size); > + retval = usb_parse_endpoint(ddev, cfgno, config, inum, asnum, > + alt, num_ep, buffer, size); > if (retval < 0) > return retval; > ++n; >
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c index 5f40117e68e7..21291950cc97 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -203,9 +203,58 @@ static const unsigned short super_speed_maxpacket_maxes[4] = { [USB_ENDPOINT_XFER_INT] = 1024, }; -static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum, - int asnum, struct usb_host_interface *ifp, int num_ep, - unsigned char *buffer, int size) +static bool endpoint_is_duplicate(struct usb_endpoint_descriptor *e1, + struct usb_endpoint_descriptor *e2) +{ + if (e1->bEndpointAddress == e2->bEndpointAddress) + return true; + + if (usb_endpoint_xfer_control(e1) || usb_endpoint_xfer_control(e2)) { + if (usb_endpoint_num(e1) == usb_endpoint_num(e2)) + return true; + } + + return false; +} + +/* + * Check for duplicate endpoint addresses in other interfaces and in the + * altsetting currently being parsed. + */ +static bool config_endpoint_is_duplicate(struct usb_host_config *config, + int inum, int asnum, struct usb_endpoint_descriptor *d) +{ + struct usb_endpoint_descriptor *epd; + struct usb_interface_cache *intfc; + struct usb_host_interface *alt; + int i, j, k; + + for (i = 0; i < config->desc.bNumInterfaces; ++i) { + intfc = config->intf_cache[i]; + + for (j = 0; j < intfc->num_altsetting; ++j) { + alt = &intfc->altsetting[j]; + + if (alt->desc.bInterfaceNumber == inum && + alt->desc.bAlternateSetting != asnum) + continue; + + for (k = 0; k < alt->desc.bNumEndpoints; ++k) { + epd = &alt->endpoint[k].desc; + + if (endpoint_is_duplicate(epd, d)) + return true; + } + } + } + + return false; +} + +static int usb_parse_endpoint(struct device *ddev, int cfgno, + struct usb_host_config *config, int inum, int asnum, + struct usb_host_interface *ifp, int num_ep, + unsigned char *buffer, int size) { unsigned char *buffer0 = buffer; struct usb_endpoint_descriptor *d; @@ -242,13 +291,10 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum, goto skip_to_next_endpoint_or_interface_descriptor; /* Check for duplicate endpoint addresses */ - for (i = 0; i < ifp->desc.bNumEndpoints; ++i) { - if (ifp->endpoint[i].desc.bEndpointAddress == - d->bEndpointAddress) { - dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n", - cfgno, inum, asnum, d->bEndpointAddress); - goto skip_to_next_endpoint_or_interface_descriptor; - } + if (config_endpoint_is_duplicate(config, inum, asnum, d)) { + dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n", + cfgno, inum, asnum, d->bEndpointAddress); + goto skip_to_next_endpoint_or_interface_descriptor; } endpoint = &ifp->endpoint[ifp->desc.bNumEndpoints]; @@ -522,8 +568,8 @@ static int usb_parse_interface(struct device *ddev, int cfgno, if (((struct usb_descriptor_header *) buffer)->bDescriptorType == USB_DT_INTERFACE) break; - retval = usb_parse_endpoint(ddev, cfgno, inum, asnum, alt, - num_ep, buffer, size); + retval = usb_parse_endpoint(ddev, cfgno, config, inum, asnum, + alt, num_ep, buffer, size); if (retval < 0) return retval; ++n;
Amend the endpoint-descriptor sanity checks to detect all duplicate endpoint addresses in a configuration. Commit 0a8fd1346254 ("USB: fix problems with duplicate endpoint addresses") added a check for duplicate endpoint addresses within a single alternate setting, but did not look for duplicate addresses in other interfaces. The current check would also not detect all duplicate addresses when one endpoint is as a (bi-directional) control endpoint. This specifically avoids overwriting the endpoint entries in struct usb_device when enabling a duplicate endpoint, something which could potentially lead to crashes or leaks, for example, when endpoints are later disabled. Cc: stable <stable@vger.kernel.org> Signed-off-by: Johan Hovold <johan@kernel.org> --- Exploiting this to trigger a crash probably requires a lot more malicious intent than the syzbot fuzzer currently possesses, but I think we need to plug this nonetheless. Johan drivers/usb/core/config.c | 70 ++++++++++++++++++++++++++++++++------- 1 file changed, 58 insertions(+), 12 deletions(-)